Your MC sessions sound just like mine. We could be pleasant and talkative right up to the session, but in the session it was like she was telling herself "I am not going to be forced to work on this, I'm not, I'm not, I'm Not!" - Silent, sitting as far away from me as possible, not looking at me, not answering questions, etc.
I don't think this is abnormal for our Sitch's.
In our early sessions, My W still maintained that the EA was minor and over and not really worth discussing. When it came out (I brought it up after finding more evidence) that the EA was still ongoing, had never really ended, and was pretty serious, then our MC ended the joint sessions right then and there. It was his opinion that joint MC can not work as long as there is a 3rd party in the picture. We have each been going through IC with him with the plan to pick up joint MC again if and when she decides that the EA is over, is no longer pursuing it, and decides that she want's to work on the M.
You may want to consider the same.
Me 42, W 39, S8, S6, S2 M 11y, A & ILYBNILWY 11/08 Walking away from a bad situation.
