Why don't you just ask her. It might just take your "ordinary" sex life into the realm of "really hot stuff". If you feel uncomfortable asking her these types of questions ask for her opinions on porn what she likes etc.
Felt the need to post the same question again? I still stick with what I said the first time around. It could very well be fantasy only with her. Just because she likes reading stories on a certain subject, that doesn't mean she wants to act out those things.