Are these red flags?

I’ve been dating my boyfriend for 3 years, and over the years my boyfriend’s actions have been questionable. I’m 20 but he’s 25, so maybe it’s my fault for expecting him to act his age and mature. He doesn’t really behave inappropriately with me that much anymore, because I communicated my feelings with him after the first few times I felt disrespected.

However, I really don’t know if he loves me or is lusting over me. Once he constantly kept calling me sexy, and I had to ask him if I wasn’t sexy would he still be with me... and he said tbh probably not. I appreciated the honesty, but I was baffled. When I told him that was a little shallow, he told me everyone has to be attracted to the person before they initiate the first step of dating. While I agreed, I didn’t believe that applied to my question, because outer beauty fades as we age so it shouldn’t be a big factor if you love the person.

Anyways, his cousin is my best friend, and his cousin has told me that multiple times my boyfriend has talked about random girls that he thinks are attractive when they go out with the boys. He’s the only guy who does this, and he’s the only one actually in a relationship... Apparently, my friend “jokingly teases” him that he’s going to tell me (even though I was told afterwards). I usually brush it off, because its nothing new since he has done it before in front of me. Plus we all are wired to notice when someone is attractive. I still notice when I see a guy hotter than my boyfriend (He kind of let himself go and stopped going to the gym everyday with me when we started dating). I just feel like he goes too far with it though. Like now I kind of feel embarrassed when people tell me this. I feel disrespected, instead of him talking about me, he talks about other women to our friends. Yet, he gave me a promise ring and tells me that he wants to propose to me after I graduate from college? I really did see it happening, but stuff like this makes me rethink if he is even ready for that stuff. I get so annoyed and question if he really loves me for me. Age is really just a number and at times I feel more mature than him. I’m not sure if this is a red flag? How do you put up with immature men?