I don't think we can control other people; who they are friends with, who they are attracted to and interested in and make comments about. All we can control is ourselves and how we feel about ourselves.

I think you need to become better friends with yourself so what your boyfriend is doing in his life isn't quite as important. Let him be who he is; he may or may not stay interested in you, that isn't something you can control. But if you are interested in yourself and doing interesting things, that is most likely to attract others. Try to relax about your boyfriend and what he's doing and he'll be more likely to tell you about it if he doesn't feel you are going to judge or disapprove of him or his friends.

No one else outside of the relationship can break you up if neither you nor your boyfriend want to be broken up so just "ignore" the other people. Work to become secure in who you are and then you won't need so much outside validation and other people telling you about their own business. If you really trust your boyfriend, you won't be so concerned with what he's doing when he's not with you; he's just living his life as you should be when you're not with him.