I think most people aren't used to being rewarded for direct honesty. And this is more so for women. I know that my INTP friend had a problem with their partner for a similar reason -- the person was intimidated by my INTP friend. Which makes it really hard to have a relationship with someone.
When I encounter harshness or dismissiveness in my friends (INTP/ISTJ) I know if I keep pushing, my friends will really think about what I'm saying. They're reasonable otherwise I wouldn't be friends with them. In addition to being the type of person who likes to push, I feel secure and invested enough in our relationship to push.
Maybe the woman you are involved with has felt she has had to push you about other topics -- perhaps seemingly mundane topics like what you thought about a movie or politician -- but she takes it that this is how you will respond to any critique she may have of you? And she feels uncomfortable in general 'pushing'.
I think periodically reminding the woman that you really value her opinions and want to her to feel comfortable around you -- BEFORE these eye opening conversations -- will help.
Perhaps it's a question of tell don't show or show don't tell, and some people take more warming up before telling you how they feel, even if something is bugging them and no matter how much you try to tell them to tell you when something is bugging them. Sometimes you can't 'force' people to tell you what they think if they are still in the formulation phase of those thoughts and getting comfortable with that opinion themselves. In those cases, I just think that's the way they deal with things and it's not necessarily an issue to fix or that I can fix. I have friends like this.