From my very limited view, I can tell you my H treats ow in much the same way. He can ignore me, and I know he ignores her. Over the last 2 weeks, it has made her livid. It has not however made her leave.
Lightbulb went on earlier this morning. He has stated repeatedly that she will go away. By doing the ignoring, he is hoping she will. Instead he gets very carefully worded messages. So does your H treat ow the same? I would imagine so. Especially since he gives you the responses about he doesn't care where/who he ends up with.
Seems to me they (yours and mine) do care. They just don't know how, don't have the strength or don't want to be responsible for the hurting, to end it with one of us.
Aliens!!! Wish I had an answer!
When you can't make a decision because you are torn between your heart and your head, listen to the half with the brain.