Hey! I can totally relate to your dilemma, I've had a very similar issue with my husbands friends especially when we first started dating.

A few of them have warmed up to me over the years but the bulk don't like me very much and it's pretty much for the same reasons you've listed - when me and him started dating he spent significantly less time partying and doing drugs with them and they blamed it on me. You have some really great advice in other comments but I want to tell you one important lesson in all of this that took me a long time to learn. My biggest realization was realizing that I really don't care at ALL what these people think of me, I'm secure in my relationship and ultimately I'm dating my husband...not them. They can dislike me all they want but at the end of the day I'm in a happy, healthy, secure relationship and they aren't going to change that. My husband knew that I put an honest to God effort into fostering a healthy relationship with them, and if he felt the need to take their side when I gave up...well at least I knew where he stood and knew to move on.

I understand you are in a slightly different situation, but just remember that dating their friend doesn't make you obligated to be friends with them too. If your boyfriend wants to hang out with them, plan on not being around. I never see some of my husbands friends and I'm perfectly content with that. It does complicate things that he lives with them, though.

But, to sum it up, retrain yourself to not care what someone thinks of you if they clearly have no regard to foster a friendship. That was their choice, not yours, and I'm certain your boyfriend knows you made an effort. Sure it kind of sucks to think about what they're saying/thinking about you but, train yourself not to care about a single thing these people do! Once you let go of the desire to be liked by them you'll realize how big of a relief it is to be rid of the pressure and that forgetting about being liked or disliked by them will make you so much happier.