Current models of sexual responding emphasize the role of contextual and relational factors in shaping sexual behavior. The present study used a prospective diary design to examine the temporal sequence and variability of the link between sexual and relationship variables in a sample of couples. Studying sexual responding in the everyday context of the relationship is necessary to get research more aligned with the complex reality of having sex in a relationship, thereby increasing ecological validity and taking into account the dyadic interplay between partners. Over the course of 21 days, 66 couples reported every day on their sexual desire, sexual activity (every morning), and relationship quality (every evening). In addition, we examined whether the link between these daily variables was moderated by relationship duration, having children, general relationship satisfaction, and sexual functioning. Results showed that the sexual responses of women depended on the relationship context, mainly when having children and being in a longer relationship. Male sexual responding depended less on contextual factors but did vary by level of sexual functioning. Several cross-partner effects were found as well. These results verify that relational and sexual variables feed forward into each other, indicating the need to incorporate interpersonal dynamics into current models of sexual responding and to take into account variability and dyadic influences between partners.