Gave it back

I gave my boyfriend back his promise ring and told him to give it back when he decided what he really wanted. He says that he wants a serious relationship and he wants to settle down. But then he goes and talks to random women and has a bunch of naked pictures on his phone. I don't know what to believe. I think he likes the thrill of being risky and secretive because he never did anything with anyone else when we were secret FWBs and when we first started trying out dating but didn't tell anyone yet. But once we came out and we didn't have to do things secretively, that's when the trouble started. I wanna leave but at the same time I don't. I have never felt this way towards any man in my life. I'm just so confused about everything right now.