I can share with you some observations I've made over the years. Every once in awhile there will be a member who will actually welcome a non-accepting partner. I know this seems counter-intuitive, but it does happen. These CDers say they are embarrassed to dress in front of their partners, or they don't feel comfortable doing it. Several CDers didn't want the CDing to go any further than it had, and they rather liked having the sort of built-in control of not having the opportunity to dress whenever they might want to.
This forum is filled with people who for the most part, have accepted the CDing within themselves. But there are lots of CDers out there who haven't and who wouldn't dream of joining a forum such as this one, even though privately they might occasionally go to the trans porn sites. Or just lurk here. And I'm guessing that even for many of our members, there were years of purging cycles and wishing this would go away. I can't begin to describe the conflict that many GMs experience when they feel urges to dress as women, especially when combined with a fear that their SOs might think they are "lesser men" for doing this. Male socialisation is very strong and if someone doesn't have the personality to be flexible, or perhaps even the right background, it's not unheard of they would hate to see a feminine identity in themselves. So in this case, the barriers to the Cding are internal just as much as, if not more than, the external barriers of non-accepting spouses.
If there is such a thing, you need to find a forum of CDers who haven't accepted themselves and ask about why your friend behaves the way he does. You might find answers there that are closer to his truth.
My SO told me, way in the beginning of our relationship, that it was important for me to not always assume that he wanted to dress and more important, to always respect when he didn't. Not to sound like Yoda, but everyone must follow their own path.