This is a guess, but I would bet that he is as insecure about this as you started out to be (maybe still are). From what I've read on this site it's not only SOs who don't know what to do/think, it's the MTF transgenders who are also very confused about who they are, how they might be treated (by anyone, not just you), and what it all means. The fact that he's not ready to show you his femme side in full regalia tells me that he's not at all secure at the moment. It may very well end up that you are the one to ask him to allow you to meet his femme self.
One last thought: He/she is still the same person. Now that you know there is a strong feminine self, it may be that this part of "him" really is attractive. My wife really discovered Tina, and is very clear that she enjoys Tina's company. Of course, that makes Tina and I much more confident, but since I'm not yet totally sure who Tina is, or how much of me is Tina, I still have moments of unsurity. My wife and I talk about Tina as a person, but what we are really talking about is the ideas/thoughts/actions that comprise Tina. Maybe that compartmentalization can help both of you define this third person in your relationship!
Our hopes are with both of you!
Tina
