People can change within a relationship. If his time spent with his friends is innocent and just him exploring who he is and experiencing something different, as his partner, you could just be patient and not oppositional. Give him space and hope you both get closer when he’s burnt out on the friends.

But, also be aware that his time spent away from you, may be that he is wanting to be away from you, maybe looking for someone else.

I know that’s a disconcerting thought. But it’s a possibility.

If it were me, I’d probably be patient about it and wait and see. (Use condoms)