She did tell me she didn't want to be in a relationship when I first asked her out. She also gave me a long talk about how she just wants to make new friends. It was confusing because she talked in length about her ex, asked me a lot about my ex, and talked about the times guy friends she had misread her and tried to make a move on her. I kind of assumed I was already delegated to being sort of "gay best friend" since she was so comfortable talking about her period right off the bat. I was there just to help her with work and get food, so I didn't think much of it. But that fuck buddy comment got me thinking. I'll push the boundaries further when I see her again.
You're right about how things are so much more apparent after the fact. I'm terrible at thinking on my feet.