My b/f does not talk to me about what goes on in his therapy sessions. He's worn out after them and sometimes it takes days before he's back to himself. We've talked about it and he's told me he just doesn't want to talk to me about it because there is stuff that he and his T talk about that is so personal and so emotional for him that he just can't, so I don't ask. I give him his space for as long as he needs it after he sees his T and then we just go on with our lives. He brings things up to me every now and then, but short of that, we don't talk about it.
The only time we discuss a therapy session is when it revolves around our relationship. The rest of it is between him and his T.
Just let him know you're there if he wants to talk. Show him your love and respect his wishes to sort it out. Therapy can be extremely draining and many times brings up memories and thoughts that your guy probably needs time to process before he talks to you about it, if at all.
It's not a reflection on you; it's just something your b/f needs to work through on his own and with his T.
If you fall down 10 times, Stand up 11.