If you look at the trends, rape fic, bdsm, and incest are pretty big right now. For examples I'll use 50 Shades of Grey, which is terriablly written but a best seller, Monster/Dinosaur erotica is pretty big for Amazon downloads, and the Mortal Instruments series of books which has the main love intrests as brother and sister through most of the first 3 books. Make of it what you will but those are the trends I've noticed lately in female fiction.