I have been going for therapy for nearly a year; my therapist wants me to be"OK", but has recognised and understood my need to stand. She rightly thinks I should look after myself rather than focus on H and his problems, and is concerned about the effect on my mental health of my prolonged stand, with H neither going completely or coming back. In other words, I should have ways of protecting myself from his madness (boundaries).
As for MLC itself, my therapist and my psychologist friends recognise that there are times in which people undergo cognitive and emotional reorganisation, particularly men of a certain age. However, we all conclude that MLC is not one single thing, with a single cause, progression and conclusion. It's a crisis, certainly, and often midlife, but not always. People don't progress through definite "stages"; psychology shows that in a number of areas. There's a good article on this site about that.
So if people don't recognise MLC, it's not because it exists or not; MLC is not a clinical term, but relates to a group of pathologies with varying symptoms, progressions and outcomes. It is important that the clinician recognises what we want from our clinical relationship, and that we are realistic about what we can expect from our abberant spouse.