People often feel mixed and conflicting feelings (i.e., ambivalence) toward their romantic partner. So far, research has primarily shown that ambivalence is linked to negative outcomes in relationships, but is this always true? Building off the affect, behavior, cognition model of ambivalence, the present work tests the idea that, when ambivalent, individuals can experience both positive and negative cognitive and behavioral responses toward their partner. This idea was tested in three different studies with people in romantic relationships: a cross-sectional international study (n = 665), a 10-day daily diary study (n = 171), and a 12-day daily diary study with two follow-ups (n = 176 couples and nine individuals). Across studies, when people experienced greater subjective ambivalence (i.e., explicitly reported feeling mixed and conflicted) toward their partner, they spent more time thinking about the difficulties they faced in their relationship but also about ways in which they can make it better and, in turn, engaged in both constructive (e.g., wanting to spend more time with the partner) and destructive (e.g., ignoring or criticizing the partner) behaviors toward their partner. Ambivalence was also associated with greater fluctuations in both constructive and destructive behaviors daily and over time. This work advances the current knowledge about ambivalence in romantic relationships and further demonstrates that individuals can experience both positive and negative cognitions and behaviors toward a partner when ambivalent. (PsycInfo Database Record (c) 2024 APA, all rights reserved).