As Delia said a lot of it may have to do with the fact that its a o/l relationship. But if we are going to generalize, my Dom is a very quiet, very even tempered and very closed man. Now coming from a large and loud family I found that soothing and attractive - most of the time. Every now and then (lets say about once a month, ) I would get very frustrated because I had to drag everything out of him. And it wasn't because he kept secrets, it was either because of his "whats done is done, no point in dwelling" attitude or because he didn't want to worry me, ie. he was trying to protect me, . What I did is, I learned to read him - his eyes, his body language, between lines.
With time we have gotten ( I have trained him, hehehe) to a place where he no longer keeps secrets from me, tells me all the big stuff and is relying on my counsel. But much of our communication is still non verbal. He told me recently that when he travels alone he misses having me there just to look over and give me that look and have me understand.
However I doubt we will ever come to the point where he gives me minute details of his every day. And frankly who would want that, to live with a male chatterbox? I need my peace and quiet, thank you very much.