Ambivalence (i.e., “mixed feelings”) is a common and consequential experience in romantic relationships, but not much is known about which aspects of relationships are likely to elicit it. We investigated whether romantic jealousy (experienced by the individual and perceived in one’s partner) is associated with stronger ambivalence toward the partner. Four studies (N = 1,466; participants from the United States, the United Kingdom, and the Netherlands) employing cross-sectional, daily diary, longitudinal, and experimental methodologies showed that experiencing romantic jealousy and perceiving one’s partner as romantically jealous are positively associated with ambivalence toward the partner. Participants experiencing higher jealousy reported simultaneously higher perceived partner mate value but also lower trust toward their partner, which in turn increased feelings of ambivalence. Furthermore, participants who perceived their partner to be more jealous saw them as simultaneously highly committed to the relationship but also untrusting, in turn increasing feelings of ambivalence. These findings contribute to the literature on ambivalence in romantic relationships by highlighting an important relationship dynamic that increases ambivalent feelings.