Why do me and my best friend fight ALL the time?

Well, it depends what you argue about. Honestly it could be that you are either growing apart or you are starting to like each other in a different way. If you thing your friendship can take that new angle then maybe you can see if you think his is interested in you that way too. BEWARE! You might have to wait up on him, most guys connect the dots a little slower at these things, or maybe he has been waiting up on you. If that is the case and you like him back go for it, before he loses the feeling since you don't return it. Good luck!