When to end a relationship?

My boyfriend and I have been dating for 1 year.
I started questioning my relationship with him once he started commenting on other girls. I told him I don't like him doing that and he was confused as to why I said that. He would make me feel like shit about my own body. I'm scared that if I don't have the perfect looking body he would start fantasizing other girls. He went to the gym once and said that girls were talking about there ass next to him and he told me that there asses are not even that big, and that mine is bigger. Tbh I dont take that as a compliment, I dont know what to think. I’m I overthinking it?
When to end a relationship?
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