People often tell others about recent daily hassles. Such social sharing of emotion is often assumed to support affect repair, but empirical evidence points to the contrary. We tested the notion that social sharing primarily serves relationship closeness, rather than immediate affect repair. Using dyadic experience sampling with N = 100 couples, we captured social sharing in everyday contexts and assessed socioemotional implications for speakers and listeners. Across M = 87 individual measurement occasions, both partners reported potential social-sharing episodes following daily hassles and rated their momentary negative affect and relationship closeness. Global evaluations of relationship closeness were assessed at baseline and 2.5 years later. Social sharing involved both affective benefits and costs, but it predicted momentary and long-term increases in partners’ relationship closeness. These results suggest that sharing bad news in relationships may not primarily serve immediate affect–repair functions. Rather, it may be a catalyst for creating and nourishing relationship closeness.