The ubiquity of social media has provided romantic partners the permanent means of keeping tabs on each other’s activities and whereabouts. However, little is known about the reasons why some partners employ such monitoring behavior and how it affects their romantic relationships. Therefore, this study draws on attachment theory (Bowlby, 1969) in order to predict social media partner monitoring and examines how this behavior affects feelings of jealousy as well as happiness triggered by social media. The results of a quantitative online survey (N = 550) indicated that anxious attachment positively predicted social media partner monitoring mediated by trust. However, there was no significant relation for attachment avoidance. Furthermore, social media partner monitoring predicted both social media jealousy as well as social media relationship happiness. Yet, monitoring was a stronger predictor for jealousy than happiness in relation to social media. Attachment anxiety was positively related to both social media jealousy as well as relationship happiness, whereas attachment avoidance was only positively related to social media jealousy and negatively related to social media relationship happiness. Implications of the findings are discussed and directions for future research are presented.