I have a friend who's entirely high femme, and who has decided, therefore, that she can't call herself a feminist, because in her head those things are mutually exclusive.

Oh wow, that really is unfortunate. I mean! Seriously. Another example, I think Jane Austen was all about this: writing stories by, about, for women: they might be considered frivolous by some (precisely because they are *about women*) but now we consider them to be great novels, you know? Feminism is not saying that women necessarily have to be like men to be considered important and worthy.