Crying was never something I did in relation to therapy, but I sometimes felt very uneasy after sessions, worse than before, and dissatisfied. I think the intense emotions can be related to the fact that therapy is so unnatural... we go there with a lot on our minds, high expectations and anticipating the meeting for days prior - then all the highly personal interactions and whatever we perceive from it - then suddenly it is cut off because the time is up. It is really not a natural way of interacting, especially when it comes to highly emotional matter.

I experienced similar intense emotional states when in relationships that were strictly time-constrained, i.e. we could be together for several hours or 1-2 days periodically, then had to separate because we were living in different places and other factors. I remember one such relationship in particular that was very disorienting and stressful and I did not understand initially why. I was often in a sort of dissociated state and very desperate for a day or two after the meetings, with all kinds of intense reactions from crying spells to intense anger to sometimes feeling as though the familiar surroundings were alien to me. It was often very disturbing and a few times I impulsively wanted to break off the relationship because I could not tolerate it.

You probably feel that way after MC and not so much after your individual T sessions because you are much more involved and preoccupied with your MC, beyond your marriage issues. I think it is a natural reaction, probably like a sort of sudden withdrawal effect following a highly charged encounter even if the actual content of the discussion is not so deep.