So I have been with my lovely boyfriend for a few years now, everything is perfect apart from my jealousy problems. He has never cheated, is a very loyal honest guy and does not flirt with any other girls. My problem is this.. when we first got together he did not show any other interest in other females but last year I saw him looking on instagram at a picture of a half naked woman. I was so angry! We had parked by a shop and I offered to run inside and when I came back without intentionally looking at what he was doing, he was on that picture and quickly closed it. Ever since then I am a paranoid state and whenever I leave him when he is on his phone I get anxious and worked up at what he is probably doing. Anyway, a few months after this happening he started following slutty fitness models on instragram who post pictures in their underwear everyday. This got me angry because if he enjoys looking in his own time privately then fair enough but why follow them so that everyone can see and he doesn't miss a single picture they post.
When I confronted him about being angry and hurt by this, he said its natural and every guy does it. We got into an argument and he admitted to looking at other females in public and checking them out which i already knew because he stupidly does it when he is with me. He doesn't make it obvious but I can always tell
We have had so many arguments about him being attracted to other women but he said he is never going to unfollow them because all his other friends with girlfriends do it and their girlfriends don't care. His other argument is that me asking him to do that is me asking him to stop being a man.
On one side of the argument I can see his point, all humans find other humans good looking, even myself (but at least I don't feel the need to follow male models or even acknowledge them). He isn't going to act upon his attraction which i know. But on the other side I am infuriated that he cannot stop himself looking when is with me and I shouldn't feel paranoid that every time I leave the room he is checking out other women.
Anyway, sorry for the massive paragraph
What im trying to ask is girls... what would you do if you were me and how would you stop letting it get to you or solve this problem. Thank you very much in advance, all replies are appreciated and I will reply to all of them!