Couple Ethical Purchase Behavior and Joint Decision Making: Understanding the Interaction Process and the Dynamics of Inﬂuence

: We present in this paper a qualitative study of couple ethical purchasing behavior, based on interviews with French consumers. The analysis of joint decision making allows us to distinguish between ethical couples who favor the choice of ethical products when making purchase decisions together and unethical couples who do not. Our results show that ethical couples are characterized by a positive exchange of information, use of verbal and tactical persuasion strategies, and trust in the knowledge of the partner, while unethical couples are characterized by a negative exchange of information, difﬁculties with joint decision making, and conﬂict-minimizing strategy. Time, money, and pleasure appear as the most critical factors restricting couples’ purchase of ethical products. Our research provides the ﬁrst empirical evidence about the dynamics of inﬂuence of one partner over the other within couples regarding ethical purchasing behavior.


Introduction
Sustainable development is a critical concern of states, researchers, and the public. The United Nations' 2030 Agenda for Sustainable Development highlights the need for drastic changes in consumption and production modes [1][2][3]. The transition towards a more circular economy is one of the key paths to achieving sustainable development goals [4,5]. By making their consumption sustainable, consumers share a part of the responsibility in this transition [6]. Sustainable consumption refers to the use of services or goods that respond to basic needs and bring better life quality to contribute to minimum use of natural resources and toxic materials as well as the production of waste and emissions of pollution so as not to jeopardize the future generations [7,8]. In this paper, we are interested in a specific aspect of sustainable consumption, namely consumer ethical purchase behavior [9][10][11][12]. We especially aim to understand couples' decision making dynamics driving ethical or nonethical purchases.
Over the past several decades, many studies have focused on consumer ethical choices [13][14][15][16][17], investigating the drivers of ethical purchase behavior. However, most prior research has focused on decisions made by individual consumers. Yet, many decisions regarding consumption in general, and ethical purchasing in particular, are taken at the family level, within a more or less collective approach. They often involve both spouses and even sometimes the children, who are increasingly involved in this family decision making process because of their awareness of ethical issues in their daily lives. Only a few studies have considered the dynamics of influence within couples regarding ethical purchase decisions [18][19][20]. Compared to an individual decision, a joint decision often implies concessions from one partner when the points of view on the best product to choose or the purchase criteria differ. If such an influence exerted by one partner over the other one exists, it seems crucial for sustainability research to highlight how decisions regarding ethical products are made within the couple or the family.
This paper aims to fill the gap in prior literature by investigating communication within couples and couples' decision making processes regarding ethical or unethical products. The theoretical interest of this research lies in the association of the concepts of ethical purchases and decision making within a couple. We thus explore the links that exist between these two concepts to provide a better understanding of the decision making process within a couple and the dynamics of influence in the context of ethical product choices. From a managerial point of view, the results of our study may enable managers to understand the mechanisms that will promote the success of their ethical products and use them more effectively.
Our research builds on an exploratory qualitative study involving fifteen consumers engaged in couple relationships. We undertook semi-directive interviews oriented towards the dynamics of influence of one partner over the other concerning the purchase of ethical products. The analysis of the interviews allowed us to distinguish between the couples who usually succeed in reaching an agreement about ethical products when purchasing together and those who do not. Our results suggest differences in interaction strategies, information exchange processes, and decision making. Ethical couples are characterized by a positive exchange of information, tactical and verbal persuasion strategies, and trust in the partner's knowledge. Unethical couples are characterized by a negative exchange of information and conflict-minimizing strategies. Time, money, and pleasure were identified as the main factors that block couples' consumption of ethical products. We also found that the respondents unanimously expressed a desire to improve the ethicality of their consumption while their desire to see a change in their partners' behavior is limited. The results also reveal factors that seem to influence couples' ethical purchase behavior, such as the length of the relationship, the presence of children, couple revenues, revenue distribution, and the balance of power within the couple.
The article is organized as follows. Section 2 presents the research background. Section 3 develops the methodology. The results are presented in Section 4. Section 5 discusses our main findings and Section 6 presents our conclusions.

Literature Review
Ethical purchase behavior can be defined as consumer purchase of products based on ethical issues and moral laws, human rights, and environmental protection [9,10]. Most prior research on ethical product choices has focused on the behavior of individual consumers [14][15][16][17]. However, most decisions to purchase ethical products are made more or less collectively, at the couple level. These decisions involve interactions between the two partners who may have different individual attitudes regarding ethical products and need to reach a joint position before purchasing [21][22][23][24]. In the absence of literature directly addressing ethical purchasing by couples, we organize our literature review into three parts. We first analyze the decision making of ethical consumers, then couple decision making, and finally, we focus on the limited literature that addresses ethical consumption decisions within the family.

Ethical Consumers and Their Ethical Purchase Decisions
The literature regarding consumer purchase behavior shows that the values of individuals play an important role when deciding to engage or not in ethical consumption [25,26]. Ethical consumers are "influenced by environmental, social justice, human health, and animal welfare issues in choosing products and services encompassing, alongside with fair trade goods, 'sweat-free' clothes, 'cruelty-free' cosmetics, energy-efficient appliances, and organic foods" [27] (p. 505). Ethically minded consumers seek to express their values through purchasing or boycotting behavior. Yet, people often compromise their values and needs when making product choices. For example, consumers buying organic food make a trade-off between the high cost of the good and the social benefit of their decision. This routinized trade-off can explain why consumers' values do not always translate into acts.
The literature shows that some consumers express willingness to purchase ethically, but their actual purchase behavior remains unaffected by their verbalized ethical concerns [28][29][30][31]. This gap between what consumers say they are going to do and what they actually do is referred to as the attitude-behavior gap [32][33][34]. The attitude-behavior gap can be explained by consumers' limited knowledge about unethical behavior or limited time to consider the ethical aspects of their purchases [35]. Many consumers are also suspicious of the integrity of companies. Furthermore, consumers may express willingness to make ethical purchases, but they may be reluctant by the inconvenience caused. Using a Decisional Balance Scale [36], Freestone and McGoldrick [37] show that ethical decisions are most often the result of compromises between gains and losses consumers are not necessarily aware of.
Many studies analyzed the factors that influence purchasing ethical products and the attitude-behavior gap [17,38,39]. These studies identified different types of values that predict consumers' ethical attitudes or intentions, such as emotional values [40], social values (altruism), or epistemic values [15]. Ertz and colleagues [41] showed that contextual factors (having more or less time, money and power, or control) influenced pro-environmental behavior. Moreover, Tran and Nguyen [42] highlighted the importance of situational factors (income, price, availability of products) that influence purchase intentions. In addition, personal characteristics are essential in the ethical decision making process [43,44]. Ethical consumption has been studied in various domains such as energyefficient household appliances [14], organic food [15], purchasing upcycled products [16], or green hotel visit intention [17].
Despite these numerous contributions, past research has mainly covered the ethical purchase behavior from an individual perspective [15,45] and not among couples. The objective of our paper is to complete this research stream by addressing this gap.

Couple Decision Making as an Interaction Process
Couple decision making differs from individual decision making [18,21,22,46]. The outcome of a joint decision depends on the interaction process between the two partners and how they solve conflicts and reach agreements [47]. A couple's decision making process can be affected by various factors. For instance, the relationship duration is likely to play an important role. At the beginning of the relationship, couples spend a lot of time agreeing on a decision, while older couples tend to make more autonomous decisions [48]. In addition, the differences in reciprocal influence may depend on social norms (e.g., sexual stereotypes), partners' contributions to the common resources, the interest of the partners in a given decision, and their knowledge of the subject [49]. The influence of each partner may also depend on the history of past decisions. In other words, the present decisions are based on the outcomes of decisions made previously. For Kirchler [50], each partner's influence on joint decision making depends on the quality of their relationship and the predominance model within the couple. For example, the strongest partner can decide in an authoritarian relationship by forcing the other's opinion. The degree of "harmony" in the relationship (i.e., emotional aspects such as love, empathy, satisfaction, and cohesion) and "the balance of power" (i.e., the dominance structure based on hierarchical aspects) also influence the couple's decision making processes.
The notion of conflict plays an essential role in understanding joint decision making within couples [47]. When partners have different views because of divergent goals or values, disagreement may arise [51]. However, the partners do not necessarily perceive their disagreement as a conflict when working towards the same goals. The intensity of conflicts can thus range from minor differences between the partners' ideas to serious disputes about their goals and values [46]. Brandstätter [52] identified three different types of conflicts: probability conflicts (i.e., the partners have the same goal, but their opinions differ regarding the advantages or disadvantages of each option), value conflicts (i.e., fundamental differences in partners' goals), and distribution conflicts (i.e., based on the allocation of costs and benefits, where one partner might argue against an option that would primarily benefit the other partner). In value and distribution conflicts, partners usually try to find a solution by relying on their negotiation skills and various influence tactics to persuade one another. Such persuasion strategies aim to change the opinion of the partner. They are exercised utilizing several influence tactics [53] based, for instance, on the exchange of objective information or arguments, showing emotions, bargaining, etc. The partners may also use conflict-minimizing strategies, which are directed towards a reduction in the potential conflicts with the partner [50]. The use of interaction strategies depends on the quality of the relationship, the type of conflict, the duration of the relationship, the marital satisfaction, and the predominance model in the couple [48]. The harmony of the relationship seems to play an important role, with happy partners trying to find integrative solutions and buy less often on their own.
While the literature highlights the importance of the interaction between partners in explaining joint decision making, the information is scarce regarding the within-couple interactions in the context of ethical purchasing.

Dynamics of Influence within Family in Relation to Ethical Consumption
The literature on consumer behavior in general and on ethical consumption, in particular, has mainly focused on individual consumer choices [14][15][16][17]54,55]. However, many purchase decisions are made within the family or the couple and involve the two partners to different degrees [21][22][23][24]51]. The purchases of ethical products or the adoption of ethical behaviors are decisions where family members' interactions play a fundamental role. For instance, household waste management decisions, the choice of transportation modes, or energy-saving investments are successful ethical practices when they involve all family members.
Ethical consumption practices usually involve more than one household member [18]. For instance, one family member may influence household participation in green practices such as waste management, which requires a certain degree of co-action between household members [56]. Only a few studies have analyzed the ethical behavior of the consumer by considering the topic at the couple level or the family level [19,20]. Grønhøj [18] studied decision making about ecological practices within the family. The study examined how family members may influence the propensity that each other will act more sustainably through daily communication. The results have shown that ecological consumption is an important issue in Danish families. Women generally initiate the purchase of organic products within the household. In some families, the influence of one partner may lead the other partner to consume organic food. In other families, this influence has no effect on the other family members. In the majority, women influence their husbands, who accept and then adopt the ecological practices, and their children, who are educated to consume and ask for organic food [18].
The influences regarding ethical consumption and ethical purchases may be passed on from parents to children, but children may also be able to socialize with their parents [57,58]. Then, the siblings may influence each other, and spouses may influence one another through daily interaction [59]. A family member can influence the behavior of the other family members in a more or less sustainable direction. A change in behavior can thus be qualified as either "positive" or "negative" from the perspective of environmental sustainability. This behavior change depends on the content of family communication about consumption issues and the motivations for engaging in these practices. Interactions can result either in "influence" when one partner is concerned with the purchase of an ethical product and has tried to persuade the less concerned, or "intervention" in case of disagreements, i.e., reprimanding the less concerned because of their attitude against ethical behavior [18].
Despite these initial findings, the current understanding of the influence that partners exert on each other within couples regarding ethical purchase decisions is limited. Therefore, we aimed to conduct an initial exploratory analysis of French couples of consumers to understand the main factors affecting their choice of ethical products. From a theoretical point of view, our focus is on the dynamics of influence within couples. Our research objective is to understand couple communication and interaction processes and the use of influence strategies resulting in an evolution of couples' ethical purchase decisions over time.

Methodology
To understand the dynamics of influence within couples regarding ethical purchase behavior, we conducted a survey based on 15 semi-directive in-depth interviews with French consumers involved in long-term couple relationships. Our research process relies on a qualitative approach, which is considered particularly useful for providing insights into phenomena that are new or relatively unknown by the researcher [60,61]. Our research methodology is thus justified by the exploratory nature of our research. In the absence of prior literature dealing with couple interaction and decision making processes regarding ethical purchasing, in-depth interviews appeared to be better suited than a quantitative approach, based on questionnaires. Indeed, interviews allow the respondents to express freely their point of view, without being confined to a pre-defined set of ideas, identified in advance by the researcher [61,62]. They are particularly useful to acquire new reliable, sensitive, and valid information about a phenomenon which is not yet well understood [63].
Contrary to quantitative studies that generally rely on large samples, qualitative research is often based on small samples [62][63][64]. One of the main criteria used to ensure the validity of qualitative research findings is thematic saturation [62,65]. This technique implies that the interviews are stopped when the comments collected become redundant, no longer allowing for new themes to emerge in the analysis [61]. Our sample size was determined applying this saturation criterion, which led us to a sample composed of 15 interviewees with varied profiles both in terms of professional situations and age groups [66]. This size may seem small, but this number is consistent in qualitative research [67,68]. For Guest et al. [64] and Marshall et al. [62], thematic saturation is often reached in qualitative research based on the first ten to twenty interviews.
The sample consisted of consumers living together as a couple (either married or cohabiting couples), with or without children. We only retained for the study respondents from couples with both partners older than 25 years and who declared more than two years of common life. The age of participants varied between 25 and 67 years old. Our objective in recruiting the respondents was to include different profiles of couples. Forty percent of participants were men. Eight couples, about a half of the sample, declared having children together, with a number of children that varied from 1 to 4. We also included in the study two young student couples who declared low incomes (less than 1000 euros per month for each partner) and three couples with both partners aged over 50 years. The length of the relationship varied from 2 to 39 years, with a mean of 12 years.
Each interview took between 40 and 60 min. All interviews were based on a semistructured interview grid, which was the same for all participants. This grid was organized into three main parts. The first part concerned the ethical purchase decision of the couple. In this part, we asked the respondents to discuss their joint decision making with their partner. Two main ideas were explored: (1) whether, in joint decisions, their couple favors ethical or unethical product choices, and (2) if they generally succeed or not in reaching a joint position regarding the choice of ethical or unethical products with their partner. The second part dealt with the influence that the partner exerted on the respondent's ethical/unethical purchase decisions. In this part, we asked respondents if they are more ethical alone or when deciding with their partner and why. The third part of the interview asked questions about the intention to evolve towards more ethical product choices, either by changing oneself or by trying to change the partner. Following the recommendation of Toti and Moulins [13], we conducted individual face-to-face interviews rather than focus groups in order to reduce biases related to vulnerability, social desirability [69], and self-presentational concerns [70]. These biases may arise during an interview dealing with themes related to ethics.

Results
Following the method proposed by Baumard et al. [71], our data analysis involved a first stage in which the initial ideas contained in the transcriptions of interviews were organized based on a free-floating reading. In the second stage, the items were classified according to their similarities and by differentiation using an inductive approach. According to their common characteristics, these elements were later regrouped into categories and subcategories. The processing of the data collected from the participants is in line with the analytical approach of grounded theory since it is based on the construction of items through content analysis [61,72]. We used a conventional approach to content analysis, implying that categories were derived from data during data analysis in order to gain a richer understanding of a phenomenon [73]. Two researchers conducted the content analysis to ensure its trustworthiness: the first researcher conducted the analysis, and the second researcher followed up on the whole analysis process and categorization [74]. We discussed when our opinions regarding the categorization were divergent. The final phase of data interpretation allowed us to propose a framework of the decision making process in couples regarding ethical purchases.
The analysis of the interviews highlights three main results, which we present below. The first refers to the relationship between the couple's joint decision making process and ethical purchase behavior. The second concerns the reciprocal influence the partners exert over each other, allowing us to identify the factors that block couples from choosing ethical products. Finally, we analyze the intended behavioral changes and the strategies that respondents use to influence their partner towards ethical purchasing.

Couples' Decisions and Ethical Purchasing
The analysis of the relationship between joint decision making and ethical purchasing allowed us to identify two types of couples: the ethical couples who, most of the time, opt for ethical products choices when making consumption decisions together, and the unethical couples who generally fail to reach an agreement that favors the purchase of ethical products. Eight couples in our sample were qualified as ethical and seven as unethical based on these definitions. The main characteristics of these two categories of couples are described below, with a particular focus on their interaction and decision making process.

Interactions and Decision Making within Ethical Couples
Analyzing interactions and decision making within ethical couples highlights three main features that are developed hereafter: (1) a positive exchange of information between the partners, (2) the use of persuasion strategies to convince the other partner, and (3) a general attitude of trust in the knowledge of the partner.
Positive Exchange of Information. Ethical couples are characterized by a positive exchange of information between the two partners that precedes the moment when a product choice is made. Most of the time, this information exchange aims to highlight the positive features of the ethical product compared to the unethical product and the benefits of an ethical purchase decision for the couple and society. In ethical couples, the differences in point of view between the two partners are not considered as a problem, but as the starting point of a positive and constructive discussion. The most ethically oriented partner tries to convince the less ethically oriented partner of the interest in purchasing ethical products. For instance, Respondent #2 (woman, 25 years, 3 years of common life) explains: "It is him who pushes me. It is since I am with him that I become aware of many things at this level . . . to get me to eat organic products. So, it's positive, if we have divergent opinions! He often wants to eat better than me". The quality of the information exchange process between the partners appears as an essential determinant of couple ethical purchase behavior. Thus, Respondent #7 (man, 50 years, 20 years of common life, 1 child) explains: "Sometimes we have difficulties in understanding each other, but if I succeed in convincing her, we end up by purchasing the ethical product. Now, I always try to say to her that it is perhaps better to do 'that' than 'that'. She tends to follow. When we buy something, when we make projects, it is still necessary to discuss it together. And, even if sometimes the outcome depends on the product, we choose most of the time the ethical option. I always have my ideas in mind, and she says to me: Ah! It is always the 'pro-ecological' who speaks!" These verbatims illustrate couple dynamics towards ethical consumption. Over time, we observe an evolution, with one partner influencing the other towards more ethical product choices.
Persuasion Strategies. In ethical couples, the most ethically engaged partner adopts persuasion strategies aiming to develop a positive attitude of their partner towards ethical purchasing. The goal is to reach a joint decision, as illustrated by Respondent #7 (man, 50 years, 20 years of common life, one child): "we try, both of us to convince each other, why this product rather than the other one. The final decision, we always make it together". These influence strategies cover different forms of verbal or tactical persuasion, such as showing videos, tasting products, giving information, or providing rational arguments. For instance, Respondent #14 (woman, 31 years, 7 years of common life, two children) explains the use of videos: "I, nevertheless, succeeded in convincing him by showing him videos ( . . . ) He was indifferent towards everything related to food. I explained to him why it was necessary that we change our consumption mode about food. I convinced him and he accepted", while Respondent #10 (woman, 30 years, 8 years of common life) explains the use of rational arguments: "He explains to me, for instance, that I should take something which is more ethical. He will tell me: 'It's not with 30 cents that we will be ruined!' " People also try to convince their partners by making them taste ethical products, as explained by Respondent #13 (man, 50 years, 5 years of common life): "Because, at the beginning, my partner didn't want at all bio for food. But finally, it was necessary to make her taste bio products. It changed fast! Because if I buy something bio or fair trade, for me, personally, the taste is not the same, it's slightly different. And you must make people taste these products. It's also a way of convincing people".
Trust in the Knowledge of the Partner. The trust in the knowledge of the partner plays an important role in explaining the capacity of ethical couples to reach an ethical decision together, as illustrated by Respondent #15 (man, 52 years, 14 years of common life): "It's true that, me, at the beginning, I didn't know all this. It's true that she knew much better than me this type of product, and where to buy all this. It's her who showed me all this!", and Respondent #14 (woman, 31 years, 7 years of common life, two children): "I think I'm documenting myself more ( . . . ) So, I explain things to him, and I also think he trusts me". We observe a balance of power in favor of the most ethically engaged partner based on recognizing this ethical engagement, which simplifies couple decision making by limiting discussions in the store and avoiding conflicts. For instance, Respondent #15 (man, 52 years, 14 years of common life) explains: "It's because, Honorine, she knows what products are good, and she spots them easier than I do. We do not discuss much", while Respondent #12 (man, 33 years, 10 years of common life) says: "I don't really argue about it because it's always her who has more information than me. I think her choice is always the best ( . . . ) There is at least one of us who is ethical ( . . . ) interested in the well-being of humanity. I'm proud of her!" We observe that, in ethical couples, the less ethically engaged partner appreciates and values the ethical investment of their partner.

Interactions and Decision Making within Unethical Couples
We now focus our attention on the interaction and decision making processes between partners within unethical couples who, in situations of joint decision making, converge most of the time towards purchasing an unethical product. These couples are characterized by (1) a negative information exchange process, (2) conflict-minimizing strategy, and (3) difficulties with joint decision making.
Negative Exchange of Information. The analysis of the communication process between the partners in unethical couples shows that these couples are often characterized by a negative exchange of information or by the absence of information exchanges. The lack of discussion can be sometimes explained by the fact that neither partner has an interest in ethical purchasing, as is the case, for instance, for Respondent #11 (women, 30 years, 10 years of common life, four children): "As I said, ethics, it's not really part of our preoccupations". However, in most cases, the partners fail to reach a common point of view because one of the partners refuses the dialogue while having a strong position, either neutral or against ethical product choices. Discussing the ethical investment of her partner, Respondent #4 (woman, 57 years, 39 years of common life) explains: "He is generally quite against it! It's very blunt actually! He works for a company that sells pesticides! ( . . . ) I don't think he's paying attention at all! Because it's not something that he is preoccupied with. When he goes shopping, he doesn't look at anything! It's not, in fact, on this (aspect) that he's going to base his decision". The same non-interest of the partner towards ethical purchasing is reported by Respondent #1 (woman, 52 years, 7 years of common life, one child): "So, if we're together and we choose, it's often me who's going to let it go and we're going to make the purchase that he wants, which suits him, in fact. Organic, he does not care. He is not in the current trend of ethical consciousness. ( . . . ) He has technological or efficiency criteria. He doesn't have ethical criteria; that's not his thing!" Conflict-Minimizing Strategy. Partners' interactions within unethical couples are characterized by a strategy of conflict-minimizing [50]. For instance, Respondent #1 (woman, 52 years, 7 years of common life, one child) explains her partner's choice of unethical products when shopping together: "He takes things that I would never purchase. I do not want to fight at the store! That's it! It doesn't make sense to ruin one's life! One needs to make concessions, to make efforts every day! It's important!" The same concern of avoiding discussions that may lead to disputes at the store is illustrated by Respondent #13 (man, 50 years, 5 years of common life): "A joint decision, really, either one gives in, or not! It's not really a choice . . . I gave her a choice to purchase the cheapest. To avoid disputes". Respondent #4 (woman, 57 years, 39 years of common life) also reports: "We are less angry now on this subject. But, there have been more global conversations about the fact that this planet, anyway, there cannot be organic everywhere!" In most cases, the partner who pushes toward choosing the less ethical product is recognized as having greater decision making power within the couple. In the absence of positive communication, this partner may impose his/her choices without argument. This behavior is explained by Respondent #1 (woman, 52 years, 7 years of common life): "Power of decision, clearly, it's him! He makes decisions all alone. That's it!" The higher decision making power may be due to the partner's higher income, as indicated by Respondent #3 (woman, 29 years, 4 years of common life): "He thinks we don't have an expandable income. The big expenses, that's him! He has the most finances. If he disagrees, we are stuck".
Difficulties with Joint Decision making. A closer analysis of unethical couples shows that many couples in this category fail to reach a common ethical decision together because they already have difficulties with joint decision making. In this case, the outcome of the purchase decision in relation to ethical product choices often depends on who is the purchaser. For instance, Respondent #4 (woman, 57 years, 39 years of common life) explains: "In principle, the two of us are too far apart. We do not have the same level of engagement on this subject. So, I go shopping. If I'm the one doing the shopping, it's going to be organic. If it's him, it wouldn't be organic". We observe a gender effect for many couples in this category: the woman is in charge of current household purchases, while the man is not concerned at all. For instance, Respondent #1 (woman, 52 years, 7 years of common life, one child) explains, "In fact, we do very little shopping together", as well as Respondent #5 (woman, 47 years, 19 years of common life): "Because, in fact, my husband does never do the shopping! He does not take care of anything related to home!" This last comment suggests that the engagement in ethical purchasing may also depend on the harmony of the couple's relationship and the level of personal investment of each partner in the household. Table 1 summarizes our findings about the differences between ethical and unethical couples regarding decision making, information exchange process, interaction and influence strategies, and resulting feelings. Table 1. Dynamics of interaction regarding joint purchases in ethical vs. unethical couples.

Ethical Couples Unethical Couples
Decision Making Process Joint decision making The partners "decide together" (6) The partners "do the shopping together" (5) The partners "discuss" product choices together before purchasing (4) Independent decision making The partners "do not discuss much/at all" (5) One of the partners "decides alone" (4) The partners "rarely do the shopping together" (3) In the store, the less ethical partner "takes what he/she wants" without concertation (3)

Information Exchange Process
Positive exchange of information The more ethical partner "tries to convince" the other through discussions (7) Divergent opinions are not seen as a problem (3) The more ethical partner "pushed" toward more ethical purchasing over time (3) Both partners "try to convince" each other (2) Negative or no exchange of information The less ethical partner "does not care" about ethical purchasing (5) The less ethical partner "refuses the dialogue" (4) The less ethical partner "does not pay attention" in the store (2) The partners are both "not concerned" about ethical purchasing (2) Interaction Strategies Agreement The more ethical partner "succeeds in convincing" the other (6) The less ethical partner "accepts" the decision of the partner (4) The less ethical partner generally "tends to follow" (3) Persuasion Strategy The more ethical partner "provides information" (5) The more ethical partner actively "searches information" about ethical products (5) The more ethical partner "shows videos" (3) The more ethical partner "makes tasting products" (3) Trust-based interaction The less ethical partner has "trust" in the knowledge of the partner (4) The less ethical partner "thinks the choice of the partner is the best" (2)

Conflict
The less ethical partner "does not agree" to ethical purchasing (4) The less ethical partner "ignores ethical information" provided by the partner (4) Conflict-minimizing Strategy The more ethical partner "tries to avoid disputes" by letting go (3) The more ethical partner "doesn't want to fight at the store" (2) The more ethical partner "makes concessions" (3) The more ethical partner "makes efforts" (2) Power-based interaction The less ethical partner has more "decision power" (3) The more ethical partner "does not really have a choice" (2)

Associated Feelings
Positive Feelings The less ethical partner "is proud" of partner's investment in ethical purchasing (2) Negative Feelings Partners "get angry" (3) The more ethical partner "feels stuck" (2) The numbers in parenthesis represent the number of couples that expressed this idea during the interview. The total number of couples is 8 for ethical couples and 7 for unethical couples.

Factors Restricting Couple Ethical Purchasing
To further study couple interactions regarding ethical purchasing, we asked respondents whether they are more ethical in their product choices alone or with their partner. The analysis shows that most couples included in the study are characterized by different attitudes, beliefs, and levels of engagement of the two partners towards ethical purchasing.
Only three respondents report a similar level of concern as their partner towards ethical product choices. In this case, the outcome of the decision making process does not differ depending on the partner's presence, as illustrated by Respondent #15 (man, 52 years, 14 years of common life): "The same! I do not think it influences". This similarity regarding ethical purchases can be the result of an evolution over time (as Respondent #14, woman, 31 years, 7 years of common life, two children: "Yes, let's say that we are getting closer and closer"), but it may also reflect a low level of ethical engagement for both partners (as for Respondent #8, woman, 27 years, 2 years of common life: "It's more or less the same, we buy the same things . . . We do not think too much about it").
To better understand the couple interaction process regarding ethical purchasing, we focus our analysis, in what follows, on couples with different individual attitudes. In this case, the presence/absence of the partner may affect the outcome of the decision: some people are more ethical when they are alone, and others when they are with their partner. Three factors appear systematically as recurrent themes characterizing respondents' interaction with their partner for the two groups. They concern the restrictions on time, money, and pleasure. These three factors are briefly discussed hereafter.

Time Restriction
The restriction of time is an important aspect that could limit couples' search and purchase of ethical products. Respondents who are more ethical with their partner explain that the decision process of ethical products is longer and based on an active information search regarding the different alternative products and their characteristics. Respondent #9 (man, 34 years, 9 years of common life) highlights, for instance, the more "analytical" and "rational" nature of the choice process of his more ethical partner: "She is more [ethical], she understands a bit more, she analyzes much more things. So, I become more ethical with her". Ethical purchasing is seen by respondents as involving a more complex decision making process, based on a pushed analysis of product information and on an explicit phase of information sharing between the partners: "When I am with her, because there is an exchange before the purchase of the product . . . There are, necessarily, in the exchange, criteria to be considered, information to be shared before the purchase of the product. And so, I think it will help a little bit more when making the decision" (Respondent #12, man, 33 years, 10 years of common life).
The time dimension also appears as a constraint for the respondents who are more ethical when deciding alone than when deciding together with their partner. These consumers explain that they accept better than their partner the extra-time related to an ethical decision making process. For instance, Respondent #1 (woman, 52 years, 7 years of common life, one child) declares: "I'm more ethical when I'm all alone, because I take more time to go shopping. I can compare the packaging better". The less ethical partner may be in a time-reducing state of mind that does not allow the required conditions for reaching an ethical product choice: "There's the list. He takes, he leaves. While myself, with the list, I will perhaps check to see if I can find better by quality-price ratio, stuff like that" (Respondent #3, woman, 29 years, 4 years of common life). Moreover, the "time" dimension restricts ethical product choices if neither partner takes the time to search for information, as illustrated by Respondent #8 (woman, 27 years, 2 years of common life): "We don't have time to have all the information on all the products that we buy. When we only have thirty-forty minutes to do our shopping, we are under pressure".

Money Restriction
Money also appears as an important factor that can limit couple's ethical purchasing behavior. For instance, some of the respondents who are more ethical when deciding with their partners explain that their partners encourage them to disregard the price as a purchase criterion. Thus, Respondent #10 (woman, 30  . ) It always comes into play: there is the financial side and the ecological side. So, we will try to discuss it and find the right balance".
The analysis of the interviews shows that, in general, respondents associate ethical consumption with higher prices. This is the case, for instance, for Respondent #13 (man, 50 years, 5 years of common life), "This is also the problem with all that is ethical. It's more expensive", and Respondent #15 (man, 52 years, 14 years of common life), "These are products that . . . because they are natural, are a little bit more expensive. Afterwards, it's still . . . , I repeat myself a bit, but it's still for my health. It is true! We don't have to compromise on that! I'll say to her 'there is no problem [to spend more] when we do the shopping!'" The price argument appears in the discussion between the partners as a choice criterion whose importance needs to be downsized to allow the couple to choose ethical products: "We buy the farm chickens, even if they are more expensive. And I tell her: It doesn't matter if we eat a little bit more or a little bit less! We'll eat a little bit less, but of better quality!" (Respondent #15, man, 52 years, 14 years of common life). Thus, ethical couples make an informed and conscious decision to pay a higher price for an ethical product that is understood to be a higher quality product. However, even when both partners agree, the price can still be a barrier to ethical purchasing, as illustrated by Respondent #2 (woman, 25 years, 3 years of common life): "If we had the (financial) means, we would only eat organic. If we could afford it!" Some respondents discuss the price of ethical products by making a distinction between the short-term and the long-term perspective, the latter integrating the impact on health. For instance, Respondent #13 (man, 50 years, 5 years of common life) explains: "For me, it doesn't cost 'too much'. At the same time, if I'm healthy, it's going to cost me less. . . . In the long term and in the medium term, therefore, it's profitable. But in the short term, in fact, it is more expensive". This point of view is shared by Respondent #6 (man, 45 years, 11 years of common life): "For me, it is 'less expensive'! When you hear about most of the diseases that hit us right now, they are related to all the crap that they put in animal food". Overall, our observations suggest that the higher price of ethical products is easier to accept by the couple when a long-term perspective including impact on health is adopted.

Pleasure Restriction
The analysis of the interaction process between the partners shows that an ethical product is also considered as restricting pleasure compared to a conventional product. Respondents highlighted the importance of the hedonic dimension that may orient the couple towards unethical purchase decisions. Asked whether she is more ethical alone or with her partner, Respondent #5 (woman, 47 years, 19 years of common life) explains: "When I'm all alone . . . Since he's working all day long . . . I'll buy him stuff he likes . . . Pleasure, I think it's less ethical!" Respondent #4 (woman, 57 years, 39 years of common life) provides the same type of argument based on the pleasure dimension to explain why her partner prefers unethical products: "Because there are things he likes to eat! ( . . . ) I'll buy the chocolate he likes. In fact, I won't fight about this!". This argument is also advanced by Respondent #11 (women, 30 years, 10 years of common life, four children): "If he likes it, he is not going to look at all for information about the brand". We thus observe that the pleasure argument is used (i) to motivate the purchase of unethical products by the couple, but also (ii) to justify a different attitude of the partner towards ethical purchasing. Respondent #1 (woman, 52 years, 7 years of common life) explains in detail the relation between the pleasure orientation of her partner and his unethical product choices: "He is more like a pleasure consumer. So, he buys what interests him without thinking. In fact, he thinks a lot about his own pleasure, the quality of the product, for instance. He would love High Tech products. He's not going to look at the price, not at all. Recycling, he doesn't care, he ignores it royally! Anyway, he has a job [doctor] that makes him have the tendency to throw away everything!" Table 2 resumes the main items that emerged from the analysis regarding time, money, and pleasure restrictions in relation to ethical purchasing.

Time Restrictions
Purchasing ethical products "takes more time" (8) Decision making process of ethical product "is more complex (rational/analytical) and takes more time" (5) Purchasing ethical products implies more time for "searching information" (5) Purchasing ethical products implies more time for "comparing packaging" (4) Purchasing ethical products implies more time "to go shopping" (3) Purchasing ethical products implies more time "to discuss" the choice and share information before the purchase (3)

Money Restrictions
Ethical products have a "higher price" (7) Existence of a "trade-off" between the financial side and the ecological side (5) Ethical products are less expensive if a "long-term perspective" is adopted (5) Ethical products are less expensive if "health effects" are considered (3) Increasing ethical purchasing by "buying less" to reduce the price (3)

Pleasure Restrictions
Pleasure is "less ethical" (6) Pleasure "justifies the purchase of unethical products" by the couple (5) Pleasure "justifies a different attitude of the partner" towards ethical purchasing (3) Pleasure increases unethical purchasing by "habit decisions" (3) Pleasure increases unethical purchasing by "impulse buying" (2) The numbers in parentheses represent the number of couples that developed this idea during the interview. The total number of couples is 15.

Couple Intention of Behavioral Change towards More Ethical Purchasing
The participants in the study were asked if they intend to evolve regarding their own ethical purchasing and if they would want to see their partners change their attitude towards more ethical purchasing. The results highlight differences between the desire to change one's own personal behavior and the desire to change a partner's behavior. Moreover, the respondents explain that the behavioral change within the couple seems easier for organic food relative to other types of ethical products. Couples' life-cycle transitional events appear as potential drivers of behavioral change. These three points are developed hereafter.

Desire to Change Couple's Attitude towards Ethical Purchasing
Most participants verbalize a positive desire to increase their own ethical purchasing in the future. At the same time, our analysis shows that respondents perceive the behavioral change as difficult and tend to postpone the implementation of this change. For instance, Respondent #14 (woman, 31 years, 7 years of common life, two children) qualifies change as "not easy" ("I think I have already taken a first step. For foods, I must admit that I try to consume organic foods, avoiding food that is GMO. It is not easy"), while Respondent #4 (woman, 57 years, 39 years of common life) makes a clear reference to the notion of "effort" ("Yes, well, I know that I make the effort when it is not too important. I go to some [food] stores that give me the opportunity to buy this type of product").
While most of the respondents declare an intention to change their own behavior, the results are mixed regarding the desire to change the partner's attitude towards the purchase of ethical products. For instance, Respondent #6 (man, 45 years, 11 years of common life) says, "I think I would like to change her", while Respondent #1 (woman, 52 years, 7 years of common life) explains, "Usually, yes! But I'm not going to make it a subject of a fight!" The difference between the desire to change one's own behavior and the partner's behavior is surprising. The consumption, especially of food products, is most often collective and not individual within a couple. The respondents who declare they do not want to change their partner's attitude toward ethical purchasing are primarily concerned with respecting the nature of their partner, whatever that may be. For example, when Respondent #9 (man, 34 years, 9 years of common life) speaks about his partner's involvement in ethical consumption, he says: "No! Because it looks like her. So I do not want her to change". Similarly, Respondent #8 (woman, 27 years, 2 years of common life) speaks about the lack of involvement of her partner as follows: "I think that in a couple it's a mutual sharing, . . . not necessarily that I prevail . . . we try stuff together, either it's ethical or not". However, age seems to affect the intention to change a partner's behavior, with older couples (aged over 40) being more inclined to change their partner's attitude toward ethical products. Lastly, in some couples, both partners are poorly engaged in ethical consumption and consider the current situation satisfactory. Therefore, convincing the partner to change is simply irrelevant (Respondent #3: "Not necessarily, because for the moment, it does not bother me").
Respondents who want to change their partner adopt influence strategies based on verbal persuasion attempts through regular discussions or tactical persuasion, such as making their partner try ethical products to demonstrate that they taste better. Therefore, a path to reinforce ethical purchasing is to avoid shopping together. Being in charge of household shopping allows for buying more ethical products and convincing the partner indirectly and in the long run (Respondent #13: "If it's me, if I buy alone, I'll take the biological product").

Easier to Convince the Other Regarding Food
Respondents' declared intention to change depends on the nature of the product. Indeed, they seem more prone to modifying their food habits and buy more organic or fair-trade products. Food is at the intersection of various concerns and motives such as environment conservation, health, or support for small producers. Several respondents explain that moving towards organic food (which is recognized better for family health) is easier to defend within the couple. For example, Respondent #6 (man, 45 years, 11 years of common life) says: "Regarding food, it's easier . . . compared to technology. When we talk about technology, it is difficult to know how to buy ethically. But if it's about food, it's something that's going inside the body; it's a sensitive topic . . . In that case, we're going to eat something that everyone is happy about. I think it's easier to convince and to be convinced to buy ethically when it comes to food". Similarly, Respondent #10 (woman, 31 years, 8 years of common life) declares: "[It is easier for] everything that is produced that we are going to consume, that we are going to eat. It's easier because it concerns us directly. For example, tomatoes: if I would like to take those from Spain, he will convince me that, you see, in France, we are surer about how it was done and so on. So, I will be more easily convinced, and so will he".

Perceived Importance of Couple Life-Cycle Transitional Events
Couples' life-cycle transitional events are seen as opportunities for evolving toward a more ethical purchase behavior. Several respondents highlighted the importance of a stable job associated with higher financial means that may increase the possibility of buying ethical products. The birth of a child is another transitional life event that can drive ethical purchasing. In particular, couples without children plan to consume more organic foods when they have children. As an illustration, Respondent #3 (woman, 29 years, 4 years of common life): "Yes! First, if I had a more stable job, I would take better care of myself. I also believe that once I have children, babies or infants, I would buy more . . . products, maybe not in fair trade but much more organic". The presence of children in a couple is a factor that strongly encourages ethical food consumption. The couples with children are concerned about ensuring a healthy diet for their progeny and about keeping informed about products (Respondent #14, woman, 31 years, two children: "I know, for example, that we consume organic products, but I also try to avoid for my children everything that is with GMO. So, I look on the website of Greenpeace and, there is such and such brand that we must avoid"). We also observe that the couples whose children are no longer at home still refer to their children in relation to their ethical purchase behavior.

Discussion
The main contribution of our research lies in the association of the concepts of ethical purchase behavior and couple decision making. Three main results emerged from our analysis. First, we showed that ethical couples differ from unethical couples with respect to their exchange of information, interaction and decision making processes, and persuasion strategies. Second, our analysis highlighted time, money, and pleasure as the three main factors that can restrict ethical purchasing by couples. Third, our results revealed several factors, such as relationship duration, presence of children, wage, or decision-making power, which influence couple decision making towards more ethical product choices. We also found that couples perceived a behavior change in favor of ethical food as easier than for other ethical products. To synthesize our results, we propose a framework of couple decision making and interaction processes in relation to ethical purchasing (see Figure 1). The framework focuses on couples where partners have different levels of engagement towards ethical products, highlighting the factors that influence couple evolution over time regarding ethical purchasing. The framework proposed in Figure 1 points out that the level of harmony in the relationship (love, empathy, satisfaction, relationship quality, and cohesion) influences couples' ethical purchasing by favoring the communication process and the desire to reach an agreement [46]. The distribution of power, which depends on partners' personal resources (e.g., expertise, money), is also a key determinant. Within harmonious relationships, the power is balanced between spouses or, at least, the more powerful partner does not exploit her/his advantage in decision making situations. Couples in harmonious relationships seek to realize their joint wishes considering the goals of both partners [77]. Therefore, harmonious couples have more chances to evolve toward ethical consumption over time. Our analysis showed that the quality of couple interaction and communication processes is one of the main factors that explains how couples reach a joint ethical purchase decision together. Ethical couples are characterized by a positive exchange of information. In these couples, the differences in point of view are well accepted and positively perceived. The partners desire to reach a common decision before purchasing, which stimulates discussions. The interactions within ethical couples are based on information management, expert influence, trust, and persuasion strategies. Information management refers to the acquisition of information from various sources, the processing and evaluation (aggregating different sources, structuring, controlling, judging the quality and utility of information), the distribution of information, and its use for decision making. Expert influence is used when one partner possesses technical knowledge and expertise about a specific product and wants to convince by providing information on the different alternatives. The less ethically engaged partner has trust in the knowledge of the most ethically engaged partner. This explains why he/she tends to follow. This trust-based interaction strategy can optimize the decision making process by limiting discussions. The partners succeed in reaching an agreement because the more ethical partner manages to convince his/her partner. A large panel of persuasion strategies are employed, not only based on verbal persuasion (arguments) but also on tactical persuasion (showing videos, making the partner taste products). Our results are thus consistent with the persuasion strategies described by Spiro [53]. Positive feelings such as satisfaction, pride, and trust are experienced during the interaction process of ethical couples.

Conclusions
The harmony characterizing the relationship of ethical couples is in line with previous research, which found that happy partners try to find integrative solutions and buy less often on their own [48,51]. The agreement to purchase ethical products is associated with syncratic decision, which consists of a joint decision made by couples who choose to buy ethical products [75]. The less ethically engaged partner will tend to evolve over time, becoming more aware of ethical consumption.
Unethical couples are characterized by a negative exchange of information or an absence of information exchanges between the partners. If one of the partners has knowledge regarding ethical products, this knowledge is either not recognized or not valued by the other who may not be aware or not pay attention to such products. In unethical couples, partners usually try to impose their point of view in an attempt to persuade one another. The outcome of the interaction process can be explained by an unequal distribution of the balance of power in favor of the less ethical partner. According to resource theory, the balance of power is determined by the comparative resources of both partners [51], for instance, in terms of education, income, or competence. The more powerful partner (here, the less ethical partner) uses her/his superior role, and the less powerful partner (here, the more ethical partner) is expected to let it go. The most ethically engaged partner adopts a conflict-minimizing strategy to avoid fights in the store. This strategy is in line with Kirchler's study [50] and consists of acting to reduce potential conflicts with the partner. When conflict-minimizing is used to persuade, it generally results in autonomic decisions, which refer to decisions individually made by one spouse or the other which are imposed to the partner [76]. In unethical couples, the conflicting situation may persist even after the couple chooses an ethical product in the store. This gives way to negative feelings such as anger or feelings of oppression for the most ethically engaged partner who needs to make concessions, make efforts every day, and let go or give in. The main strategy of influence used by the most ethical partner to increase their couple's ethical purchase behavior consists in doing the shopping alone. Indeed, when partners do not shop together, they do not need to reach an agreement, and the outcome of the decision depends on who makes the purchase.
The framework proposed in Figure 1 points out that the level of harmony in the relationship (love, empathy, satisfaction, relationship quality, and cohesion) influences couples' ethical purchasing by favoring the communication process and the desire to reach an agreement [46]. The distribution of power, which depends on partners' personal resources (e.g., expertise, money), is also a key determinant. Within harmonious relationships, the power is balanced between spouses or, at least, the more powerful partner does not exploit her/his advantage in decision making situations. Couples in harmonious relationships seek to realize their joint wishes considering the goals of both partners [77]. Therefore, harmonious couples have more chances to evolve toward ethical consumption over time.

Conclusions
Our research enriched prior sustainability literature by providing a deeper understanding of the within-couple dynamics of influence in the context of the purchase of ethical products. The qualitative analysis based on interviews showed that ethical couples were characterized by a positive exchange of information, the use of persuasion tactics, and trust in the knowledge of the partner. Their relationship was based on harmony, with positive feelings of respect, pride, and satisfaction. In contrast, unethical couples were characterized by a negative exchange of information, conflict-minimizing strategy, and difficulties with joint decision making. Our results provide an alternative explanation for the attitude-behavior gap for consumers living in a couple: the intention of the more ethical partner to consume ethically may not turn to action because of the reluctance of the less ethical partner. Overall, our analysis allowed us to clarify the interaction process between the two partners in the context of ethical purchasing and the factors that may contribute to a joint ethical purchase decision. In particular, the results showed that couple ethical consumption might increase when one of the partners actively contributes to reducing (i) the pressure of time by providing information and reducing information search time, (ii) the pressure of money by providing extra purchasing power or encouraging to disregard price as a purchase criterion, and (iii) the influence of pleasure by encouraging a more rational decision.
Our research has important implications for managers. By providing a more complete understanding of the dynamics of influence and the interaction process within couples concerning ethical purchasing, our findings may allow managers to better identify the mechanisms that will contribute to promoting ethical products. Companies could act on the three factors identified as restricting the ethical purchasing, namely, money, time, and pleasure. By downsizing the importance of these factors through marketing and communication campaigns, companies selling ethical products may achieve the goal of encouraging couples to buy their products. To reduce the prevalence of money restriction as a choice criterion, companies could highlight the long-term benefits of the ethical products for health (egoistic value) or environment (biospheric value) since both are likely to engage consumers in purchasing more ethical products [78]. Companies could also reduce time restrictions by making their packaging more transparent and thus helping consumers reduce the time spent researching about ethical products. Finally, our results show that moving towards ethical consumption can be associated with a restriction of pleasure as consumers have to change their habits or give up products they like. Companies could develop the hedonistic dimension of ethical products, emphasizing the improvement of well-being and the better quality of life driven by the consumption of ethical products [79,80].
The results presented in the paper are a first step in understanding ethical purchasing by couples and call for future research on this topic. First, quantitative studies should be conducted on larger samples to confirm the observations of the present research. This study mainly covered the situation of purchasing food. Future studies could extend the analysis to other product categories such as household products, power source choice, etc., and distinguish between high and low involvement purchases. This would allow us to explore the interrelation between several ethical consumption contexts and highlight how these different facets of ethical consumption complete each other. Second, since we observed that ethical purchase behavior of couples might evolve, future research may conduct longitudinal studies to gain a better understanding of this interaction process over time, implying status change, presence or absence of children, or age progression. Because children directly influence the purchase decision process, it would be important to focus on their role and age within different contexts of ethical purchasing. Third, our study was limited to French couples. An international comparison should be carried out, as cultural aspects exert a high influence on couple consumption and financial behavior.