Previous research has outlined synchronies between romantic partners’ everyday affect, health, and well-being, but it remains unclear whether similar processes take place for real-life cognitive abilities and whether there are age differences. The present study investigates the coregulation of cognitive functioning using the example of prospective memory (PM), the ability to remember and correctly execute future intentions. Over 21 days, 61 younger (aged 18-33 years) and 38 older couples (aged 57-86 years) completed an ambulatory assessment comprising a daily PM task. Specifically, we examined the impact of social proximity (i.e., physical closeness and psychological intimacy) on the dyadic coregulation of daily PM. Results revealed that partners’ PM performances appeared to be coregulated - independently of whether partners had physically met. In men (but not women), this coregulation was more pronounced on days with greater intimacy and more time spent together. The results were not moderated by age group. In conclusion, the present study indicates that romantic partners coregulate their everyday cognitive performances and that both the physical and psychological dimension of social proximity may impact couples’ daily PM performance. Importantly, this implies that relationship quality is essential to a more fine-grained understanding of underlying effects in everyday cognitive processes.