This thesis shows how critical life events and life transitions impact on different dimensions of the relationship quality of men and women. Furthermore, it is examined how conjugal interactions intervene between critical life events and transitions and relationship quality. The study is based on the longitudinal Swiss survey «Social Stratification, Cohesion and Conflict in Contemporary families» which provides information of both partners of a couple in two points in time. The results show that critical life events and transitions which are related to the professional life are from great importance for the relationship quality of men and women. Conjugal interactions have additive effects on this impact. Additionally, fusional couples show higher relationship quality than couples where partners are autonomous from each other. In conclusion, if we want to understand conjugal relationships, it is important to consider external and internal factors.