My partner really gets me: Affective reactivity to partner stress predicts greater relationship quality in new couples.

Affective reactivity, defined as within-person increases in negative affect triggered by daily stressors, has well-established links to personal well-being. Prior work conceptualized affective reactivity as an intrapersonal phenomenon, reflecting reactions to one's own stressors. Here, we conceptualized reactivity interpersonally, examining one's responses to a romantic partner's daily stressors. Across four longitudinal dyadic studies, we investigated how reactivity to partner stress predicts relationship quality appraisals. In fledgling couples, reactivity to a partner's stressors, assessed via weekly (Study 1; N = 152) and daily (Study 2; N = 144) diaries, positively predicted partner relationship quality. In both studies, the associations were mediated by the partner's perceptions of responsiveness. Furthermore, reactivity to partner stress buffered against declines in partner relationship quality over 8 weeks in Study 1 and 13 months in Study 2. The relevance of reactivity to partner stress for relationship quality diminished in the later stages of relationships. Among samples of established couples (Studies 3 and 4, Ns = 164 and 208, respectively), reactivity to partner stress did not directly predict partner relationship quality or moderate its trajectory over time. Overall, the predominant pattern across four studies painted a portrait of relational well-being benefits specific to fledgling relationships. Through its novel framework of situating affective reactivity interpersonally between partners, the present research contributes to both affective science and relationship science. (PsycInfo Database Record (c) 2024 APA, all rights reserved).