Welcome to our forum.
There is always a chance that someone can change, but in this case I admit that it seems like your boyfriend will not change. (Whether he theoretically *could* change is another philosophical topic.)
I hear you that he is not a bad person or anything, but it just sounds like the two of you are not compatible. I agree with you, he should consider being polyamorous, rather than just cheating all the time. But that's his call, you can only make suggestions to him, you can't decide his decisions.
There is no 100% guarantee here of what you should do, but those are my impressions based on what I've read. Hope things work out for both of you guys.
Love means never having to say, "Put down that meat cleaver!"