Good day Sue,
I have been pondering your sitch for a while now, and it seems that for you, your sitch has developed and taken a different direction than most. I'm not saying its better or worse, just different. As most others transition into a detached state, few really achieve total detachment and on occasion push/search for some kind of feedback from spouse as to their state of mind. The one positive outcome is that we do get some insight into what their issues are and what there approach to those issues are at the time and over time we can see them working to make some sort of progress in whatever direction.
In your case, Sue, you have done such an exceptional job of detaching from his issues and don't push for any feedback along with unfortunately him not offering any, is really keeping you in the dark as to how he is progressing with his issues and that must be very tough to deal with too. . So Sue, we understand your frustrations and there is no reason we would be hard on you.
I know you have mentioned he is not much for expressing himself, but I wonder if encouraging him to open up some about himself would bring you closer. This could achieve a couple of things. One ... it will continue to fortifiy you do have an interest and want to be supportive in what he is working through, and thereby still show you care for him. Two ... it will give you a better understanding of what he is going through and hopefully shed some light upon you so you won't feel so much in the dark.
Focus the questions and strictly keep the subject about him and not how it relates to you or "OR". Ask the questions with a positive slant. Perhaps start it off with saying how you notice how much more relaxed he seems lately ... good for him ... so in some ways things must be improving for him ... what is getting better? Try to keep the conversation directed as one friend that is concerned for another.