I think Adam tries to avoid thinking about Shane. He just, really doesn't want to dwell on it because every time he does he gets upset. Because he won't do that, he's still stuck dwelling on that betrayal and hurt which isn't healthy either. Eventually though, he's going to think about it and he's going to be upset haha. He probably misses just talking to him like a normal person the most. Like, aside from the physical intimacy there's that whole layer of their relationship that's lost.
Yes, they still see each other. Yes, they can even still have a professional relationship, but that's not really enough for him after he's had a lot more. That and he probably misses having Shane close in general.
I think about Adam doing something or seeing something he knows Shane would enjoy and instinctively looking beside him and Shane isn't there anymore so it's like, oh.