BlueCreek

I think it's pretty natural for people to keep some things to themselves, no matter how close and intimate the relationship. We are still individuals with our own thoughts and minds after all. As swedish said, as long as the secrets aren't anything that would hurt the other spouse or the marriage, I wouldn't worry about it too much. Obviously if she's hiding something that would hurt you or stress your marriage, that's one thing, but I doubt that's it.

In any case, you already know part of the reason she won't talk to you about it. You've previously existed in this pattern of pressing her and her pushing back. It's natural for her to react that way, it's not "sharing" when you feel like one person is pushing you into it, and it's normal to fight back. So even though now you guys are trying to work on these things together and open up communication, the past is still in your minds. She has already felt you press her on this before, and so sharing private emotions and thoughts may take more time and effort. And remember, you're talking about something incredibly personal. You may feel you have the right to know about what she is thinking about when she's in the mood, but maybe there wasn't anything specific in her mind, maybe it wasn't something she was comfortable talking about or putting into words. Then the second you push her, she pushes right back and all of a sudden she's angrily saying "there are things I'll never tell you" when really, they are probably few, far between, and pretty minor. But just being pressured makes everything all of a sudden blown out of proportion.

Maybe the next time you do bring this up with her, think about why you want her to share first. Is it so that you want to know everything she feels so that you can be better about getting her in the mood in the first place, or is it you imagining she's thinking of something you wouldn't like and that's why she won't tell you. If it's the latter, it's almost certainly all in your head. If it's the former, just explain it to her that way. Apologize to her for that night, and tell her that all you really want is to know is how to make her happy and what gets her in the mood the most so that you can always do your best to please her. Just ask her if there is anything you can do to help her feel more comfortable talking about those intimate things, but at the same time let her know you're not pressuring her to talk about it. If she doesn't want to share them yet, let her know it's ok, then maybe ask her if it's ok if you bring it up again some time down the road when you've reached the point as a couple that communication is more open and unforced.

You guys are on the right track, just remember to take things slowly. You don't need to have all the answers and 100% open communication all at once. You haven't had that for a long time, so it just takes a while to build those things back up. Remember, if you push too much too consistently it can create an emotional overload of sorts and cause her to shut down more than continue opening up.