I'm rather late for this discussion, but I wanted to add my support for Thundarr's point of view, amd RCR's subsequent follow up. It's very easy for any of us to label someone's behaviour according to our perspectives and understanding, and there are dangers in that. That is my understanding of what he is saying.
He has a very sane and rational approach, just as RCR herself. This sanity is what attracted me to this site. This site also gives hope where others do not. It gives us a way of coping. It gives support, more than any other I've seen.
Yes, we do end up diagnosing our spouse. It's natural to try and make sense of the situation we are in. Some people take a more religious approach, other a more scientific one, but the idea of this site is that we move forward from our initial shock and hurt, grow, change.
But while we analyse our spouse's behaviour, and work on our own, it's worth remembering Thundar's point. We know something is wrong, something has changed beyond our control, and our spouse is not the person we remembered them to be. We may be able to fit their behaviour into the categories that we see here. It still does not mean that it's MLC. It is a crisis, and part of it is ours as we try to cope. But if we have expectations that they will follow some predefined pattern and emerge from their tunnel and subsequent stages like a butterfly from a crysalis, some of us will be very disappointed.
RCRs ideas are wise, and whatever I think about MLC or not, I continue to find this advice wise. Work on ourselves, detach and protect ourselves as much as possible from the spouses abhorrent behaviour, drop all expectations, and leave our spouse to make their own decisions. Not easy to do. If we do that, it won't matter if it is MLC, PD, or an invading alien.