My boyfriend isn't cheating, but his best friend is a girl and they have a wierd relationship that I dont like

There are very few guys that have girls as best friends and not at some time let it go further. Im sorry to say but I think you need to move on. No you dont have a right to say anything. Your boyfriend should and if he wont then he isnt respecting your feelings. You shouldnt have to tolerate anything and neither should he. If you arent happy by now , you probably wont be. So forget the sucking it up dump him.