Yeah, sometimes perceived reality and the real reality are two things. And there are places where you can't walk on the streets as a woman. I'm not sure if it's about fear in your case. Or just because you broke your promise but there isn't any fear involved.
Anyways, in relationships general advice is to talk to each other. Ask her what's bothering her. Maybe it's a pretend reason and there is something deeper that's bothering her. Maybe this was the proper reason. Maybe she's a resentful person. Maybe she just had a bad day.
Unless it happens regularly or there are other factors to it, I wouldn't necessarily attribute it to malice or be a manipulation strategy...