do guys masturbate to other girls because you’re not good enough?

And im not talking about porn, I genuinely don’t care about porn. my ex I recently broke up with I found out masturbated to pictures of girls that we both knew on Facebook, his coworkers, people we went to school with. It just made me feel like it was because I wasn’t good enough. Is that why a guy would do that or is it something else? It’s just kind of destroyed my self esteem and I don’t want to believe that it’s because I wasn’t good enough, but that’s really what it feels like