The transition to parenthood involves numerous stressors. Consequently, many new parents report negative changes to their sexual desire, sexual satisfaction, and relationship satisfaction relative to pre-pregnancy, with the most disruption reported at 3-months postpartum. While prior research suggests that dyadic coping—a couple’s capacity to deal with stress effectively and mutually—is positively linked with relationship satisfaction, little is known about how it relates to sexual and relational outcomes in new parents’ daily lives. This study examined how common and negative dyadic coping were associated with new parents’ own and their partner’s daily sexual desire, sexual satisfaction, and relationship satisfaction. New parent couples ( N = 120) completed a baseline survey and 21 days of daily diaries between 3- and 4-months postpartum. Data were analyzed using structural equation modeling. After controlling for mood, for both women who gave birth and their partners, on days that they reported higher common dyadic coping, they reported greater sexual desire, and sexual and relationship satisfaction. On days when women reported lower negative dyadic coping, both they and their partner reported greater relationship satisfaction. When women reported higher common dyadic coping, their partners reported greater sexual desire. When women reported lower negative dyadic coping, they reported greater sexual desire. When partners reported lower negative dyadic coping, they reported greater relationship satisfaction. Focusing on strategies to encourage common and reduce negative daily dyadic coping may be beneficial for sexual and relationship well-being early in the postpartum when couples report experiencing a peak in sexual and relationship challenges.