Positive affect is associated with well-being among sexual and gender minorities and couples.

Positive affect (PA) is a key determinant of well-being among sexual and gender minorities (SGMs). Despite a well-formed literature on PA's beneficial impact in other contexts (e.g., HIV care) among SGMs, little work has examined PA's interrelations with mental and relational well-being among partnered SGMs. We examined the normative trajectory of PA among partnered SGMs assigned male at birth (SGM-AMABs; <i>N</i> = 155) embedded in a longitudinal cohort (2008-2022) and associated this with key indices of well-being (depression, negative communication, relationship quality, dyadic coping). Next, we modeled PA's association with well-being among a subset of couples enrolled in this cohort (<i>N</i> = 43 dyads). Latent growth curve models suggested that PA declined over time, but that any increased PA was associated with lower depression and higher relationship quality. Actor-partner interdependence models suggested a similar health-promotive association of PA, as well as novel associations that should be the topic of future study. Collectively, these results imply that interventions designed to increase PA among SGM-AMABs should consider the dyadic context and may be successfully applied to increase SGM-AMABs' well-being.