What should i do about my friends?

Um, yes it's okay to feel that way because if they haven't been bi as long as you have and are JUST starting being bi then maybe it IS just a stage. Or maybe, once again, they're doing it for attention. I think that they (no offense) are fake. Not in that kind of way like fake, nose fake, and lip fake. But about who they are---I think that them saying they're bi is them being fake with the world about who they really are...straight(maybe). And I think that you're just trying to know the truth. You thinking about this is you, in my opinion, showing that your true and you want your friends to be true, not someone who is fake or wants attention or maybe someone who has just copied off their best friend....you. Hope i've helped!