My w is completely and totally wrapped up in spending her time with MIL. She even started dressing like MIL recently-
Sounds as if she is trying to win approval from her mother.
I would not go on dates at this time, if there are no signs of positive change. I would stop the MC, b/c it obviously isn't helping. Pulling back and going dark on her could cause her to miss that loss in her life. As long as you're available to her, she's got her cake and can eat it too.
It is not about what you feel should work in your M. It is about doing the work that gets the right results. Do what works!