Relational events are more consequential when accompanied by emotional similarity.

Shared experience - i.e. commonality in inner states such as feelings, beliefs, or concerns - plays an important role in establishing and maintaining close relationships. Emotional Similarity (ES) can be thought of as one type of shared experience, but the exact role it plays in our responses to specific contexts (objects, events, circumstances) is not well understood. We sought to examine the day-level context-dependent roles of romantic partners' ES. We hypothesised that relational events (i.e. conflict and sexual activity) occurring on days with high ES would be more consequential. Two samples (N = 44, N = 80) of committed couples completed daily diaries for three and five weeks, respectively. Each evening, partners reported their currently-felt moods, relationship quality, and the occurrence of conflict and/or sex in the preceding 24 h. ES was operationalised as the profile similarity between the partners' moods on each day. Generally, ES moderated the associations between conflict or sex and relational outcomes: on days marked by greater ES, conflict and sex had stronger negative/positive outcomes, respectively. These findings highlight the importance of considering ES on a momentary basis and suggest that it may function as an amplifier of charged relational events.