Thanks to everyone!
I met yesterday with someone who has known him professionally for a number of years & hate to say it but we had a very frank discussion. My guy is more deeply troubled than I'd even imagined - nothing dramatic like acting on a SSA or cheating on me, but just little things here & there that all add up to some "serious issues."
Rainbow - what you have said is 100% dead on: if he is not seriously engaged in recovery work, there is no sense in wasting so much of my emotional energy on this. After last night, something has happened that I have always dreaded: my love has become twinged with pity. And THAT makes it so much easier for me to disengage.
If I am not for myself, who will be for me? If I am only for myself, what am I? If not now... when? --Hillel