The present dissertation investigates the role of perceived partner responsiveness (PPR) — the extent to which individuals believe that their romantic partners understand, validate, and care for them — in affect regulation and well-being. The first paper examines mean levels and variability in affect as determinants of changes in perceived partner regard among African American couples (N = 250 individuals). Using dyadic analysis, we found that higher actor negative affect variability was associated with lower subsequent perceived partner regard. By contrast, actor positive affect variability was curvilinearly associated with perceived partner regard, with moderate levels of variability associated with higher subsequent perceived partner regard. The second paper investigates whether perceived partner responsiveness moderates the associations between daily events (positive and negative events) and daily affect (positive and negative affect). Using a nationally represented sample (N = 1313 participants), we found that experiencing daily negative events was associated with increases in daily negative affect and decreases in daily positive affect, whereas experiencing daily positive events was associated with decreases in daily negative affect and increases in daily positive affect. More importantly, perceived partner responsiveness predicted lower negative affective reactivity to negative events. That is individuals who perceived their partners as highly responsive experienced lower increases in their negative affect from a non-stressor day to a day in which they experienced at least one stressor. The third paper focused on perceived partner responsiveness as a stress- buffering mechanism explaining the association between the unfair division of housework and well-being. By sampling individuals who were living with their relationship partner during COVID-19 (N = 355 participants from 27 different countries), we found that greater perceived partner responsiveness in wave one leads to the reduced perceived unfairness of housework division in wave two, which in turn predicted greater sleep quality and positive affect at wave three. Taken together, three papers contribute to our growing understanding of perceived partner responsiveness, affect regulation, and well-being.