I am sorry you are finding yourself here but it is a good place to belong to a community of others going through similar rough times in their relationships.
As far as whether your spouse is going through a MLC our something else would be a guess on my part. While it sounds like it, with what you've shared, I would recommend that you go to the resources at the top of this section of three forum and read up on MLC.
While it would be nice to put a name to what is happening to your H, MLC can last a very long time. Regardless of whatever it is he is going through (and bringing you through it as well), read as much as you can here and in Micheles books. I would be cautious in sharing too much of what Michele reaches with your spouse, especially anything about a MLC because it can be offensive to them. I'm not an expert but I would make it a team effort with MC but keep the details of DBing to your self. Do through actions and not words.
