Stress challenges romantic relationships and can negatively impact relationship functioning. We investigated the association between daily stress and feelings of closeness toward the partner within individuals during a particularly stressful time (i.e., first societal lockdown during the COVID-19 pandemic in Germany) and examined whether a preference for coping together with one’s partner attenuates the negative effect of stress on closeness. We conducted a two-wave experience-sampling study for 7 days at the beginning of the lockdown (April 2020, Wave 1) and for 7 days 3 weeks later (May 2020, Wave 2). Participants rated the extent to which they cope with stress together with their partner once at the beginning of the study. During both waves, participants received a questionnaire on stress, partner contact, and closeness three times a day (N of participants = 272, N of observations = 6,377). Multilevel analyses confirmed the negative within-person association between stress and closeness: In situations when participants experienced greater stress than usual, they felt less close to their partner. In addition, we found a significant three-way interaction: When participants had partner contact, the negative effect of stress was buffered by their preference to cope dyadically rather than individually. Taken together, the present study found that stress was negatively associated with closeness, notably both within and between individuals. Furthermore, this association was exacerbated among participants who typically do not prefer to cope with stress with their partner, suggesting that these individuals in particular may benefit from interventions targeting coping skills at the couple level. (PsycInfo Database Record (c) 2022 APA, all rights reserved)