I agree with Sir. "act as if." She has a war raging inside. It is much easier to justify leaving if you get caught up in everything.
You showing her kindness is causing her to think and its very hard for them to do this. My wife will stay busy doing anything to void thinking. Little do they know the person their trying so hard to escape is themselves.
I used to catch my wife zoning out too. I think they do this as a "mental break" so to speak. After a while I could tell as soon as I looked at my wifes eyes (deer in headlights) what kind of mood she is in. It does change at the drop of a hat too. Try not to show anything negative.
Sounds like your doing well. Yeah "whats wrong" is a no no. They hear it as "whats wrong with YOU!" no matter how nice you say it. Deep down they know something is up with themselves. Sometimes I found saying if there is anything I have done to upset you please let me know, and say no more.
Patience my friend. and as hard as it sounds you somehow need to remember you and your little ones in all of this, its so hard sometimes to get them out of your head.