Your H is obviously confused and uncertain. No degree required to see that - right?
Confusion and uncertainty within our spouses can be a yolk around our necks. But in situations such as ours, (more specifically yours right now) confusion and uncertainty is a good sign.
It sounds as though your H is deeply bonded to you and D and all that irreplaceable history that you share.
There are pollutants of some sort in his psyche and it is causing him a load of distress. Causing you a load of distress as well.
My thoughts about your situation right now point to "loving detachment" as the most logical direction to take.
