Romantic partners can modulate each other’s emotions in many ways, resulting in interwoven emotional lives. Here, building on findings from basic psychological research, we propose a novel way of such interconnectedness, termed partner-expected affect, in which perceptions of a partner’s feelings may positively predict how this partner will actually feel at a later moment in time. We evaluated this hypothesis by means of an experience sampling study in which 100 romantic partners (50 couples) reported on the level of valence and arousal of their own feelings and of the perceived feelings of their partners 10 times a day throughout a week. In line with expectations, we found that how individuals were feeling at a particular moment was positively predicted by how their partner thought they felt at the previous moment (on top of how they felt at the previous moment and how their partner felt at the previous moment), at least when they had interacted with each other in between. This finding identifies a novel potential way in which people may shape each other’s feelings and paves the way to further examine the nature and boundary conditions of such partner-expected affect.