I think it is a combination of jealousy and feeling the grip of control slipping. The WW sees it this way, "It is okay for me to dump you and replace you. However, you cannot even look at another woman........although I may say I want you to move on, I really don't mean it. You cannot replace me with another woman. I intend to control you, so you will be there for me to use, however I see fit".
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!