Instagram models

Why does it make me u comfortable when I see that my boyfriend likes pictures of half naked or naked girls on Instagram.. like idc if he looks or anything but for some reason seeing what he likes just kinda makes my heart ache a little and puts me in a bad mood. I told him it bothers me and he said yeah I’m sorry I really don’t know why I do that. And he still does it haha I’m a grown 24 years old woman too. It’s not that I feel insecure or maybe I do?? Idk what is your opinion on this and would you care if your SO did that?? Should I press that I don’t like it and I don’t want my sisters or family seeing that or should I let it go???? Idk yet what route I wanna go...