kikifree - I have heard of some of them snapping out of it, rather than coming out of it gradually. But most of them have to work their way through it slowly, and it is slow.
I think [very much MO] that many of them cannot cope with coming in too close. Distance is how some cope best. Interesting your FIL had a MLC - my h's father was a mean sob. Sorry but that is the truth. Maybe a permanent MLC?? Now there is a thought!
I very much relate to wanting to understand about this MLC stuff. It is so devastating, and seems to have been so little studied in other than an anecdotal way. I know there are people who doubt it, but the repeated stories of a loving spouse suddenly deciding they no longer love their spouse and family, and proceeding to act in a most self destructive way suggests that someting is going on here!
I have gotten a little obsessed at times with trying to figure out what is going on, but in general I believe I am happier for greater knowledge. I interpret my husbands behaviour more dispassionately, and in some ways am less hurt by it.