I would just have a heart to heart like you did here and tell him how you are feeling. But this kind of thing happens in college anyway. Even if he looked the same as you or you guys were related by blood, you may have still suffered from changes his life is going to take. He’s trying to fit in. The fact that he invited you means he still cares for you. Maybe he just feels conflicted because he feels ashamed that he didn’t stand up for you and kick them to the curb. However,he has to start growing and changing and you aren’t always going to approve of these changes. It could be that he sees your disapproval and feels judged. My kids had the same problems during college. This probably would’ve happened sooner during your teen years but good kids usually go through this stage later in life. The only thing you can do is try to be supportive and let him know that you will always be around and will always love him. Tell him you understand that you both may not always agree on stuff or in the friends you choose but you hope you can always agree to be there for each other and support each other and still remain best friends. Oh, and welcome to fluther.