Previous research indicates that extradyadic sexual behaviors and other behaviors including emotional infidelity, pornography use, and online infidelity are considered to be acts of betrayal. However, perceptions of infidelity occurring through social media and of romantic parasocial relationships (one-sided romantic attachments formed with media figures) have not been well researched. In two exploratory studies, I examined a) the extent to which participants rated parasocial, sexual, emotional, and social media behaviors as infidelity, and b) how hurtful these behaviors would be if a partner were to enact them. I also examined how often participants reported having been negatively affected by their partner’s parasocial romances. Results indicate that activities such as sexting and sexy Snapchatting are perceived similarly to both cybersex and physical sexual infidelity, and that parasocial infidelity is seen similarly to pornography use. These similarities apply to whether the acts are seen as infidelity, and in terms of the emotional pain the acts may cause. These results indicate that extradyadic social media and parasocial behaviors can be negatively perceived, and may be likely to negatively affect real-life romantic relationships.