It won't hurt to ask these questions Vince. But be prepared that she may either not know at the time what she's getting from him or she may not be comfortable in sharing that with you. Give it time, don't push...again, perhaps bring it up in your individual session to get a feel of what your T is thinking.
Just remember she is attending MC with you so there is a great deal to be said for that. I went to MC alone because he would not go. I went to 4 DIFFERENT Christian based counselors...why 4 because I was waiting for one of them to give me hope that he was able to be the loving man that I needed...and each one of them told me the SAME thing, some people are not capable of loving anyone but themselves. They cannot give because it takes away from their self love. I learned about Narcissism. Read it sometime, that is my exH. The world does and always will revolve around him.
I highly doubt that he will become the permanent fix for her. It's a temporary fix for whatever is ailing her heart. What you want to do is to provide the safe place for her to come back to...to your heart...not push her out in the world again, without you. I didn't want to do that...but I did and now in hindsight, it was truly the best thing for me to do...but again, my exH was not like you.
I know you were off yesterday...that's why I was writing you so much to bring you back to center...there are a few on here that GET IT, and some that never will, they will just continue to chase their tail in the cheeseless tunnel. They will never face their greatest fear, themselves...it's easier to put all the blame on the WAS instead of the LBS role on the demise of the R.