The environmental impacts of the fashion industry are widespread and significant, as the industry is a heavy water consumer (approximately 79 trillion liters per year), producing 8 to 10 percent of the global CO₂ emissions and large amounts of textile waste, most of which ends up in landfills or is incinerated, including unsold products [1].

In addition to being globally popular, blue jeans are associated with somewhat problematic sustainability and social responsibility issues [2]. The traditional jeans production process uses excessive amounts of water, chemicals, and energy, thereby generating a negative impact regarding the carbon footprint [3]. In order to remove excess dyes and achieve the desired color, blue jeans are washed at least twice before being sold; globally, approximately 3% of the water used in agriculture goes into cotton production [4] to produce more than 2 billion units per year [5]. Another factor contributing to environmental degradation comprises the chemical products used throughout the production process (from insecticides and pesticides), even in cotton production, which accounts for 2.4% of the world’s arable land use; other chemicals are used to dye and paint the jeans, which have a significant environmental impact if not properly handled and disposed of in the environment [6].

Over the past decade, growing awareness of environmental issues and increased consumption have encouraged apparel brands to adopt practices that cause less environmental damage and incorporate social sustainability practices into their operations and value chain management strategies [7]. Many brands have started adopting sustainability strategies and policies to integrate such concepts and improve their image [8]. Some have started to introduce and create sustainable extensions [9]; the examples include H&M, Zara, Pull & Bear, and C&A, who have launched sustainable lines with items made from recycled and organic materials. The blue jeans market has also adapted to the new sustainability paradigm, developing substitutes for toxic chemicals, introducing resource-saving technologies, and generally applying sustainability practices and new developments in jeans supply chains, from raw material selection to the reuse of used clothing ^[10][11][10,11].

In recent years, there has been an increase in the research on consumers’ awareness and adoption of sustainable clothing behaviors [12]. An increasing number of consumers advocate purchasing sustainable fashion products to meet their psychological needs, reflecting their attitudes toward equality and sustainability. Consumers are increasingly aware of sustainability [13] and are demanding that companies take action. However, they often need to be made aware of their responsibilities and the impact of their consumption [14].

Consumers who tend to buy products from fast fashion brands prefer low prices, and according to Mandarić et al. [15], buying clothes from sustainable brands is generally not dominant in consumers’ behavior, although they show concerns about climate change and pollution; they also believe that their conscious consumption has a positive impact on the environment, although it does not yet influence their purchasing decisions when buying clothes—showing an attitudinal behavior gap [16]. In fact, consumers who are more concerned about environmental issues have the ability to choose between greener and more traditional products [17]; however, despite growing concern about fashion brands’ unethical practices, this concern is not always reflected in their behavior [18].

Consumers are often skeptical of marketing campaigns in which companies claim to be sustainable and admit that they may benefit economically from doing so; in fact, some companies advertise products as green or organic when only one element of the production process meets this claim [19]. Despite the still low levels of sustainable fashion purchasing, more and more consumers are questioning the impact of their clothing purchases [20]. This suggests that brands should provide transparent information about the sustainability impacts of their products; however, these products should remain relatively similar in style, quality, and price to conventional products to facilitate consumer choice and encourage sustainable purchasing [21].

One barrier to purchasing sustainable clothing is the need for more options; as companies work to provide more sustainable options, consumer perceptions of sustainable products compared to similar conventional offerings are changing dynamically and must be considered by brands [22]. According to Kim et al. [8], brand extensions are the application of an established brand name to new products in order to capitalize on the heritage of the original brand and capture new market segments. The inclination to accept offers for items in a sustainable brand extension can be facilitated if the consumer feels love for the brand and is loyal to it; brand love, the most intense relationship between a consumer and a brand, strengthens brand loyalty [23]. The main positive effects of brand love are brand loyalty, positive word-of-mouth, and willingness to pay a higher price ^[23][24][23,24].

2. Sustainable Blue Jeans Consumer Behavior

Brand love is a concept that has been widely researched and discussed in recent years and is related to the holistic and hedonic proposition of the brand, which ultimately leads to purchases ^[25][27]. However, brand love creates a deeper connection between the customer and the brand ^[26][28]. The difference between someone who likes a particular brand and someone who loves the same brand lies in their personal experience, which is known as their brand experience, a concept correlated to both feelings; therefore, brand love not only represents a more intense feeling than liking but also has different theoretical concepts ^[26][28]. According to Gumparthi and Patra ^[27][29], brand love results from “passionate feelings and emotional attachments that satisfied consumers have for brands”. Carroll and Ahuvia ^[25][27] define brand love as the degree of passionate, emotional involvement a satisfied consumer has with a particular brand; brand love includes passion for the brand, attachment to the brand, a positive evaluation of the brand, and positive emotions in response to the brand. These authors introduced the construct of brand love separately from interpersonal theories as a combination of interrelated behavioral, cognitive, and affective processes; they also emphasized the integration of self-expression to explain brand love (positive effect), as well as the effects of hedonic products on brand love (positive effect) and brand loyalty (negative effect). Carroll and Ahuvia ^[25][27] also make a distinction between brand love and brand satisfaction. First, brand love has a much stronger affective focus. At the same time, satisfaction is a specific result of a transaction; brand love is often the result of a long-term relationship between the consumer and the brand. In contrast to satisfaction, brand love requires no expectations (the consumer knows what to expect from the brand), involves a willingness to express love, and involves the integration of the brand into the consumer’s identity—none of which are prerequisites for satisfaction. Both the brand and the consumer interact on several levels, from the most superficial to the deepest; the latter involves a high degree of passion and emotional attachment, which can be considered brand love ^[25][28][29][27,30,31]. Consumers love a fashion brand because of the passion it inspires in them; fashion brands seek to capture and attract markets of young consumers who want to express themselves through fashion, who in turn can pass on positive feedback to other consumers ^[30][32]. Carroll and Ahuvia ^[25][27] developed a ten-item scale to measure brand love, focusing on passion, involvement, positive evaluations of the brand, positive emotions in response to the brand, and declarations of love for the brand, combining these individual components into a unidimensional construct. This approach has been criticized because many researchers consider brand love to be multidimensional ^[31][33]. Despite this criticism, Carroll and Ahuvia’s ^[25][27] concept is the most widely applied in the literature. Bagozzi et al. ^[32][26] also developed a brand love scale based on qualitative studies conducted by Batra et al. [23], which identified characteristics of brand love experienced by consumers, namely related to brand love itself and its consequences (brand loyalty, positive word-of-mouth, resistance to negative information, and willingness to pay a premium). Identification with a brand is a determinant of the brand ^[24][33][24,34] and may be more significant the more closely it is linked to the consumer’s self-concept ^[34][35]. To achieve their identity goals, consumers use brands to create and represent self-images and to present these images to others or to themselves ^[34][35]. Thus, the relationship between the brand and the consumer captures an essential part of the consumer’s construction of the self. Therefore, the primary dependent variable in theour studies measures the extent to which consumers incorporate the brand into their self-concept. In addition to their role in the construction of the self, brands help individuals convey a particular image to others [24]. As Bagozzi et al. ^[32][26] point out, not all people have a strong love for some brands, nor are all brands likely to evoke feelings of love in consumers—known as neutral or low-love brands. However, an empirical study of neutral brands by Batra et al. [23] found that 80% of the sample expressed at least some love for a brand, which was found to be predictive of brand loyalty and positive word-of-mouth. This finding suggests that even in the case of brands with low or moderate involvement, where it is unrealistic to admit to much love for the brand, some love can still be helpful ^[35][36]; brand love is a predictor of relevant consequences—such as loyalty, positive word-of-mouth, and willingness to pay a premium for branded products—and many authors emphasize the relevant role of brand love in developing and maintaining the relationship between the consumer and the brand ^[33][36][37][34,37,38]. Brand loyalty describes the desire to maintain a long-term relationship with the brand ^[38][39]. According to Chaudhuri and Holbrook ^[39][40], loyalty is a combination of underlying behavioral, cognitive, and affective processes; for these authors, brand trust and affection are essential determinants of brand loyalty. Brand loyalty can be defined as conative loyalty ^[40][41], that is, the degree to which the consumer is committed to repurchasing the brand. Based on the assumption that the brand represents subjective value to the consumer, they view loyalty as a commitment, determination, and a desire to continue the relationship with the brand ^[39][40]. Authors such as Albert et al. ^[41][42] argue that brand love influences brand loyalty. Sarkar ^[42][43] states that the relationship with passion determines the repurchase intention and that romantic brand love shapes behavioral brand loyalty. The links between passion, commitment, and brand loyalty show a possible relationship between brand loyalty and brand love ^[43][44]. Brand loyalty can result from brand love ^[25][38][44][27,39,45]. Carroll and Ahuvia ^[25][27] define positive word-of-mouth as the degree to which consumers are willing to spread positive and complimentary messages about a brand. Satisfied consumers who also love the brand are more likely to repurchase and are more likely to spread the “good word” to others ^[25][27]. Positive word-of-mouth can be understood as an outcome of a consumer’s relationship with a brand ^[30][32] and includes making others aware of doing business with a company or store, making positive recommendations about a company to others, or praising a company’s quality orientation ^[45][46][46,47]. A price evaluation is a crucial influence on consumer behavior (price-related or behavioral intentions); a fair price predicts the consumer’s willingness to pay for it ^[47][48]. In the literature, the research has focused heavily on analyzing customers’ willingness to pay as a key behavioral intention (e.g., ^[48][49]). The willingness to pay a premium can be seen as the willingness to remain a brand customer in case of an increase in the company’s price level compared to other brands ^[47][49][48,50]. On the other hand, several studies refer to the willingness to pay more for a product as a result of the development of brand love (e.g., ^[50][51]) because the consumer sees the brand as unique and without alternatives or because they want to continue to feel the emotions that the brand gives them. Brand loyalty also influences behaviors such as positive word-of-mouth ^[35][51][36,52] and willingness to continue buying the brand even after a price increase ^{[24][44][52][53]}[24,45,53,54], while mediating the relationship between brand love and these behaviors [24]. The results of a study by Hill and Lee ^[54][25] show the influence of knowledge about the environmental cause on the evaluation of sustainable brands (or those that offer consumers sustainable line extensions). The study concludes that consumers perceive sustainable products as a fit for fashion apparel brands based on their prior knowledge of the brand, on the one hand, and their commitment to the environmental cause, on the other. Consumers who are more knowledgeable about sustainability issues, namely the environmental cause, tend to develop favorable attitudes toward sustainable brands ^[55][56][55,56] and recognize the suitability of sustainable brand extensions ^[54][25], thereby influencing the purchasing of sustainable brand items ^[57][58][59][57,58,59]. Hill and Lee ^[54][25] highlight the relationship between environmental cause knowledge and consumer behavior in terms of willingness to pay a premium for sustainable items. On the other hand, it is reasonable to assume that knowledge or ignorance of sustainable alternatives to blue jeans affects consumer behavior [60]. Gender is a commonly considered variable in marketing; it is reasonable that consumers are not treated as a homogeneous segment, as there are several differences in terms of gender [61]. For example, the literature states that male consumers are more likely to take risks than women [62], which indirectly shows a high level of commitment and brand loyalty in women ^[63][64][63,64]. However, women are more likely to make impulse purchases than men [65] and report more hedonic aspects, such as emotional arousal (for example, brand love) [66]. In this respect, the levels of brand love and loyalty tend to be generally higher among women, which will positively influence their willingness to pay more for sustainable products and to spread the good word about their preferred brands to others. Age is also a characteristic that can explain different consumer attitudes and behaviors and brand loyalty. Younger consumers are generally more open to new brands because they value innovation and are less loyal to existing brands. It is possible that newer brands will have a younger consumer profile and established brands will have older consumers; on the other hand, younger consumers have less purchasing power, which will affect their willingness to pay a premium, especially for sustainable clothing, even if they value ethical consumption. In any case, the relationships between age, the brand, and sustainable consumption are not sufficiently considered in the literature [67]. Several authors recognize that gender and education level can create differences in behaviors related to clothing consumption, namely ethical or sustainable consumption ^[68][69][68,69]. Chen et al. [70] report that women are more likely to be involved in ethical consumption, receive information about ethical consumption from others (more about fashion), and feel good about being an ethical consumer. A quantitative study by De Wagenaar et al. [71] of more than 500 consumers found that women owned more clothes than men in all categories of the study (total number of clothes, including unused and used); in the same study, consumers aged over 30 owned more clothes, while those under 20 and over 51 owned more unused clothes. A study by DeLong and Bang [72] concluded that baby boomer women (members of the generation over 58) seek more mature and timeless clothing, although the same is true for younger generations, as both are influenced by an environmentally conscious culture (leading to more sustainable clothing consumption). A study by O’Cass [73] concluded that women are significantly more involved in clothing fashion than men; the same is true for young consumers compared to older ones. Pauluzzo and Mason [74], on the other hand, looked at generation Y consumers or millennials (members of the consumer generation born between 1980 and 1995), who are said to be the ones who consume the most fast fashion products (still accepted as the social norm), discarding used clothing more frequently and without considering sustainable ways of doing so. However, they acknowledge that millennials are aware of the social and environmental impacts of clothing consumption and are willing to pay more for sustainable products, which is perplexing because these attitudes and intentions do not translate into actual behavior in the same way. In addition, younger consumers are more likely to value constant change and are more prone to impulse buying [75]. Higher levels of education may also positively influence sustainable purchasing behavior [76]. A study by Rahim et al. [77] found significant differences in consumer behavior for sustainable products but did not find them in age or education level.