What to do when your best friend does not like your boyfriend?

Making you choose between them is selfish on both of their parts. I would have a long discussion with both of them, separately perhaps, about how this is making you feel torn between them. That being said, you don't have to spend time with them together, which is a relief! Just let both of them know that you value both of them, and if they care about you as well, they should both agree that taking their dislike for each other out on you is unfair.

well, i can only suggest that if you wish to keep good relations with both of them then you will have to keep them away. try not to talk about your boy friend when you are with your best friend or vice versa. it is a difficult thing but very much possible, just restrict your talking... talk aboutt he person with whom you are talking not about the other. this would make them feel important. they get into a fight because, probably, one of them feels insecured. so it depends on you to make them feel secured.