He's told me, multiple times, that he'll tell me anything I want to know. That he'll answer anything I ask, and on the off chance he doesn't want to tell me, he'd explain why.
Sometimes I wonder if I just don't know what to ask.
Some days he's more talkative, telling me things, and I find myself pausing, being quiet, because often listening is the only prompt someone needs to tell you more.
Sometimes I do ask, but I phrase my questions carefully. He's not secretive, but he is private. His past is his and some of it isn't pleasant. He isn't compelled to share everything the way I am. Hell, I probably share too much.
I want him to tell me things, but I think it doesn't occur to him to tell me without being asked.