本研究旨在探討華人文化脈絡中，婚外情歷程如何透過「緣」形塑行動正當化、倫理協商與情感意義。過往研究多聚焦於動機、發展階段與行為分類，較少關注行動者如何以緣分敘說調整其行為意義。因此，本研究以華人文化中具歷程性與詮釋性的「因－緣－果」概念為核心，提出一動態理解模型，理解行動者如何在動因、關係展開與結果反思間流動協商。研究採紮根理論，透過目的性取樣招募30位具婚外情經驗者，進行半結構式深度訪談。分析分兩階段：第一階段以開放、主軸與選擇編碼建構婚外情發展的「因－緣－果」架構；第二階段針對訪談中涉及「緣」之語句進行聚焦編碼與敘說意圖分類，並依關係不同時期分析敘說策略。結果顯示，「緣」語言在婚外情歷程中具有三項功能：（1）在關係開啟時協助行動者將難以啟齒的情感需求與婚姻困境轉化為可理解的偶遇與機緣；（2）在關係深化時用以合理化情感投入與關係維持，使行為具心理正當性；（3）在關係結束與自我反思階段，以緣分包裝結果，促進自我整合與文化可接受性。總結而言，「緣」是貫穿整段婚外情歷程的重要調適概念，拓展了婚外情發展的語言與文化面向，亦為華人社會中親密關係與倫理研究提供新的理解與實務建議。

This study examines how individuals involved in extramarital relationships within a Chinese cultural context make sense of, legitimize, and emotionally negotiate their actions through the culturally embedded concept of yuan (緣). The literature on extramarital affairs has extensively explored motivations, typologies, developmental stages, and psychological outcomes, but has comparatively failed to comprehensively address how individuals reinterpret their actions in culturally meaningful ways. The usual emphasis has been on individual choice, moral conflict, or relational dissatisfaction, while often overlooking the role of the culturally specific interpretive frameworks that allow actors to reframe ethically ambiguous behaviors in forms that preserve coherence, dignity, and emotional continuity. To address this gap, this study focuses on yuan as a narrative and symbolic resource through which individuals in extramarital relationships negotiate meaning, responsibility, and moral legitimacy. Drawing on the process-oriented and interpretive framework of “cause–yuan–effect” (因–緣–果), which is commonly found in Chinese cultural thought, this study proposes a dynamic model for understanding extramarital relationship trajectories. Rather than being considered linear or purely decision-driven processes, affairs are conceptualized in the study model as ongoing negotiations between initial motives, relational unfolding, and retrospective reflection. Within this framework, yuan functions both as a belief in fate and a flexible discursive tool that allows individuals to mediate between personal agency and culturally intelligible explanations. The framework also highlights how actors move fluidly between self-attribution, relational circumstances, and culturally sanctioned narratives as they interpret their experiences over time. Methodologically, this research adopts grounded theory as the primary approach. Using purposive sampling, 30 individuals with lived experiences of extramarital relationships in a Chinese cultural context were recruited. Semi-structured, in-depth interviews were conducted to capture the participants’ relational histories, emotional experiences, and narrative constructions across different phases of their affairs. Data analysis was conducted in two main stages. In the first stage, open, axial, and selective coding were employed to construct a developmental framework of extramarital relationships based on the “cause–yuan–effect” logic, capturing how motives, relational encounters, and perceived outcomes link across time. In the second stage, focused coding was applied to the interview segments involving references to yuan. These segments were also analyzed through narrative intention classification, focusing on how yuan-based expressions varied across different relational stages (i.e., initiation, deepening, and termination). The findings reveal that yuan-based language serves three primary functions throughout an extramarital relationship’s trajectory. First, during the initiation stage, yuan operates as a narrative bridge, transforming difficult-to-articulate emotional needs, marital dissatisfaction, or unmet relational expectations into culturally understandable encounters, coincidences, or serendipity moments. Through this framing, individuals can soften the moral tension and render the emergence of the extramarital relationship less confrontational for both themselves and others. Second, during the relationship’s development and deepening, yuan is used to rationalize the associated emotional investment and relational persistence; in invoking yuan, participants portray the continuation of the relationship as something that unfolds naturally, and thus not as a series of deliberate moral transgressions, which affords psychological legitimacy and emotional stability to the situation. Third, during the ending and self-reflection stages, narrating the relationship’s outcome through yuan allows individuals to integrate their experiences into broader life narratives. This framing supports self-reconciliation, reduces feelings of guilt and fragmentation, and enhances cultural acceptance by situating the relationship within a shared moral and symbolic order. The conclusion is that in Chinese cultural contexts, yuan emerges as a central adaptive concept woven throughout the extramarital relationship’s entire trajectory. By foregrounding the linguistic, narrative, and cultural dimensions of affair experiences, this study extends the extant models of extramarital relationship development, going beyond individualistic or purely psychological explanations. The findings offer new theoretical insights into how culture shapes ethical negotiation and emotional meaning-making, delivering insightful implications for research and practice regarding intimate relationships, counseling, and ethical discourse in Chinese societies.