He puts up the barriers. You've just asked him to make a choice he can't deal with. It's not so much having to choose that bothers him but the fact that whatever he does, he's going to be in the wrong. And chances are that he'd prefer to be the bad guy in your eyes than in his mother's, especially if he's never learned to say no to her...
Jess still can't believe she let Rob buy a minimalist kitchen
You find you're talking to yourself while he's in a world of his own wishing he was far away, and wishing you could be a bit less selfish. He'll simply have nothing to say.
A better approach