Introduction: Differentiation is a key concept in family systems theory that refers to an individual's ability to separate their intellectual and emotional processes. Spouses with low differentiation often demonstrate lower emotional maturity and have a limited capacity for intimacy and connection, which can lead to decreased relationship satisfaction and happiness. In contrast, in relationships characterized by higher differentiation, spouses are more accepting of each other's differing opinions and experience fewer emotional reactions. This dynamic fosters a deeper intimacy and leads to a happier relationship. The aim of this study was to examine the relationship between self-differentiation and the happiness and marital satisfaction of married individuals in Gonabad.

Methods: The sample size for the study was determined using Cochran's formula, which included six hundred forty participants. Sampling was carried out using a surface sampling method proportional to the volume. A key criterion for participation in the study was that individuals must be married. Data were collected using the Scowron and Friedlander Self-Differentiation Questionnaire, the Oxford Happiness Questionnaire, and the Enrich Marital Satisfaction Scale. Statistical analysis was performed using the Pearson correlation coefficient, path coefficients, and path analysis to evaluate the data.

Results: The results indicated that self-differentiation positively impacts happiness, and in turn, happiness contributes to marital satisfaction. An analysis of the direct relationship between self-differentiation and marital satisfaction revealed that while this relationship is significant, the effect of self-differentiation on marital satisfaction is less pronounced than that of happiness.

Conclusions: Self-differentiation is a crucial predictor of marital satisfaction. These findings will be especially beneficial for therapists who focus on intergenerational transmission processes in marriage.