It’s possible your ex-friend didn’t want to overstep boundaries with your new boyfriend. I know that, in the past, I have acted awkward around friends when they get new girlfriends simply because I have had experiences where new girlfriends have felt threatened by me, so I’ve learned to just back way off from a friendship and feel things out and make sure the new girlfriend is comfortable with me before I’m friends like before. Friendship always changes when someone gets a significant other anyway. It creates a whole new dynamic, so I think you have to expect that.

I would have a talk with him about how you feel and see where he really stands, that you felt he was being really off and awkward and figure out why that is. It may be a misunderstanding.