It's very sad that you have such concerns about your boyfriend. Have you talked to him about your worries? Maybe you should discuss it honestly and frankly. It could be that you've got yourself in a tizzy, so ask him directly. In any case, this should be discussed in a couple. Maybe things will get better after the conversation and you will become a little more confident in your attractiveness.

I can tell you something as a guy who watches the same content and has a girl who is a little bit lush. If I watch for example here https://hotdose.com/channels athletic girls hooking up with men and doing incredible things, it doesn't mean I don't love my girlfriend and she's not attracted for me. It's just a video, he's dating you for some reason. So he has feelings for you and you attract him. Adult content, in my opinion, is just an opportunity to fantasize about something else. Fantasy and real life are very different things. Fantasies exist to fantasize. It sounds odd, but I hope I've made it clear that it has nothing to do with real life preferences. So be confident in your boyfriend and in yourself and let go of jealousy.