Marc, there probably isn't much you can do to head off this storm. You can't control what she is going to do, but you don't want to send the message that you'll help her along in this quest. You can validate her confusion by saying something like, " It must be hard to feel so confused that you feel the answer is to move out." This way, you are not supporting or agreeing with her decisions.
I am sorry you're going through this...it may become a long and bumpy ride.
