Although adults in romantic relationships currently show more openness to online sexual behaviors [1], these behaviors can nevertheless increase couple conflicts and instability [2]. In the current study, we assess the mediating role of Internet pornography use and cyber infidelity in the relationship between 1) personality and attachment, and 2) couple and sexual satisfaction. A total of 779 participants in couple relationships (average age = 29.9 years) completed a series of online questionnaires. According to their responses, 65% of participants visited an adult site at least once during the six months preceding the study, while 16.3% did so multiple times per week. Path model results showed that Internet pornography use and cyber infidelity were sequential mediators between, on the one hand, personality and attachment, and on the other hand, couple and sexual satisfaction. The discussion highlights the importance of properly documenting the correlates of online sexual behavior to better understand new couple realities and dynamics.