How to deal with a relationship when the personalities are so different?

When I first met my boyfriend (8 years ago), he use to hang out with his friends a lot, drink extensively and do things I would never imagine myself doing. As time went on, he spent more time with me and stopped drinking. Now that I am in medical school on the East Coast, he is without me on the West Coast. He has gone back to his old habits, of going out every single night and not coming home until 5am. I mean regardless of the fact that he is not going to clubs or bars, he is hanging out at friends houses getting drunk until 5am, I just don't find it right. I mean he is 24 and at the age where he really needs to focus on what he needs to do and become. I am studying non-stop yet I am the one who always needs to make an effort because he is too busy hanging out with friends? I mean do I have a right to be upset ?