The purpose of this study was to identify the influence of self-differentiation on marital satisfaction and, specifically, to verify the moderating effects of positive affect in the relationships among self-differentiation, conflict resolution strategies, and marital satisfaction, with conflict resolution strategies mediating this impact. A total of 376 married individuals from the Eco Boomer generation (born 1979-1992) participated in an online survey for data collection. Data were collected using a self-differentiation scale, the Korea-Marital Satisfaction Inventory (K-MSI) with a general dissatisfaction scale (GDS), a conflict resolution strategy scale (ROCI-Ⅱ), and a positive affect regulation scale. The collected data were analyzed using SPSS 26.0 and SPSS PROCESS macro 4.1. The main results of the study can be summarized as follows. First, there were significant positive correlations among self-differentiation, conflict resolution strategies, positive affect, and marital satisfaction. Second, positive and negative conflict resolution strategies were confirmed to mediate the relationship between self-differentiation and marital satisfaction. Third, the moderating effect of positive affect was identified in the relationship between self-differentiation and negative conflict resolution strategies. Fourth, the mediating effect of negative conflict resolution strategies, moderated by positive affect, in the relationship between self-differentiation and marital satisfaction was confirmed. The study suggests that employing positive conflict resolution strategies during marital conflicts and accumulating positive affect between spouses are effective for enhancing marital relationships. It highlights that the effectiveness of various couple therapy models may vary depending on the individual's level of self-differentiation, emphasizing the need for tailored solution based on individual cases considering each participant's level of self-differentiation.