9s/9w1s, please help me understand how your brain works regarding saying what you're thinking.

My girlfriend is a 9w1 and I care about her a lot but being in the relationship is hard for me because I almost never know what she's thinking or what she wants. I know she has to be thinking something, everyone is thinking something at any given point, and likewise everyone wants something. But I don't know how to get her to express these things.

We've talked about this a lot, it is our biggest recurring argument. She says she has felt burdened or "forced to express a preference" or to "do interpretive somersaults" when I ask her to make even small decisions, like what she wants for dinner. But in that case the burden is just shifted to me to try to guess what she wants, and I don't think she really understands that, just like I don't understand how it feels that way for her.

Or when we're in an argument sometimes she will just shut down and go silent for like whole minutes, and it's like... there's something going on in there, it's very obvious, and it's a response to something I did or said, so why not keep me in the loop when I've said she can tell me literally whatever she's thinking?

Her response here is usually that she is genuinely not thinking anything (but... everyone is always thinking something, right?), or that "some thoughts don't need to be said out loud," which I don't understand because they're still real thoughts that really affect your stance toward a person, and not verbalizing them doesn't make them not exist. When anyone tells me something like "some thoughts don't need to be said out loud" it immediately tells me they're thinking something pretty bad about me and I feel like I deserve to know what that is? It's not like whatever it is can be worse than the worst-case scenarios I can come up with.

Her other response is that one reason she doesn't feel comfortable outright telling me what she wants is that she would feel rebuffed if she said she wanted to do something and I said no, when she didn't even have a strong preference in the first place. I don't understand this either. If you feel rebuffed wouldn't that mean you did have a preference? Otherwise there'd be no emotional attachment to it right?

Please help me to understand if any of this sounds relatable. I do care about her and I don't want to upset her and I definitely don't want these arguments to hurt our relationship. I just genuinely don't understand how a person's brain can work like this, it is alien to me.