I talked to him today and when I suggested the theory of him feeling like he'd failed me he smiled and told me to shut up. That would be a yes in Tom-nese :P So I have my answer.

However when I tried to talk to him about it and explain the sources for my depression he shrugged me off again and dodged the matter. I guess he's still not comfortable with the diagnosis... or he's just not into heart to heart talks lol