A big question would be why does she want to do that. If it's important to her and she feels that a part of herself is not being expressed, then maybe she wants to experiment with switching and maybe you and she need to figure out a way that she can do that. Can she play with others? Can you introduce a third into your experience?

Maybe she's not really thinking about the emotions of Dominance or switching, though. Maybe she enjoys the sensations you give her and she'd like to share them with you. Maybe just the thought of transgressing by topping you is erotic for her. In that case, maybe you want to let her do some sensation play with you, whether it's bondage or whatever, that you don't hate. You can add to the naughtiness and transgression by promising to "punish" her for what she's doing when the tables turn.