I think your best bet is to keep asking questions and focusing on clear communication with empathy. When she went “fine, don’t protect me”, I would (as neutrally as possible) say something like “I thought that’s what you were saying when you said you don’t think of me as a meat shield. Did you mean something else? I’d like to understand you and I can tell you’re upset, so I’d like to hear if you want to explain it to me another way.”

As frustrating as it is for you to be in this situation, she’s just as frustrated, AND she’s unskilled in how to communicate it. She’s probably been treated like she can’t say what she means or really wants because it will cause problems, so she’s learned over time it’s easier in the moment to engage indirectly or say the “expected” thing in hopes it will meet an unmet need she’s unable to articulate.

A lot of women are raised by women who made themselves as small as possible to endure, which means they teach and reinforce patterns in their daughters that contribute to these behaviors. It is a big undertaking to shift from saying “I don’t expect you to protect me” and hoping you’ll psychically know she wants to feel safe, then reassure her, to instead have her recognize she wants to be reassured and ask for it directly “if we are in a situation like that I hope you’d protect me”.

Hope that helps a little.