why is my....

hi there, Maybe your boyfriend has seen his bestfriend do things to other friends girlfriends or maybe hes been hurt by his bestfriend, look what ever it is, you need to get to talk and find out what all this behaviour is all about. His friend could be bragging about having you, but then this is me assuming, not a good thing to do... Goodluck with your boyfriend girl

First talk to him and sort out the reason.May be he loves you to much and he can't digest of your friendly moves with his friend.If this the reason leave him.As he may cause more problems to you in future though you sort out this problem now.