Help me understand men and how they think

If he knows it bothers you to do it in front of you and doesn’t respect that you’ve directly told him it bothers you, then he’s somewhat of a misogynist. There are plenty of areas where that’s culturally acceptable and normal, but it doesn’t make it okay. Sure, it’s human to have needs and feel attracted to others and have fantasies, but if your relationship is committed and monogamous, then you still come to a mutual agreement about what’s acceptable for both you and your partner to be happy. If he’s that dismissive of your needs, I’d reconsider if this is the kind of forever relationship you want. It doesn’t mean he doesn’t love or care about you in his way, but is that dismissiveness really compatible for you? There are men who don’t do this in front of their partners, even if your past experience has been mostly pairing off with men who have done it (might be cultural where you are so most are like that, or might be because you keep choosing a certain type of man that puts you down).

Again, the problem is not the fantasy aspect (assuming he’s not directly engaging with any of the other women he’s looking at), but that he knows he’s trampling your boundaries but doesn’t seem to care. Comparing yourself to what he’s looking at doesn’t help you either, as many are airbrushed, unrealistic, unobtainable looks, he’s still with you not them, etc. so the comparison will make anyone insecure and you don’t need to do that to yourself. You are good just as you are. But his continued disrespect after you’ve communicated your boundary is the issue to figure out.

I think the best way to understand any individual person is to ask them questions and go deep on the answers. Men are individuals, not a monolith.