If it's not there already because apparently 'Fantasy' is too apt a term for books in which a passive teen female "outsider" completely flukes into the true - and totally non-sexual - love of the hottest teenage boy in school merely by existing. Especially when said boy is a vampire/werewolf/zombie/etc...
While the term has apparently been around for a bit, Barnes and Noble is in the process of rolling it out to their stores now in an effort to subdivide this out of the Fantasy section so the No-Kissy-Kissy Fantasy Nerds and the Kissy-Kissy Fantasy Nerds can stop throwing daggers at each other whilst tripping over opposing turf. This is probably also where I should point out my amusement at the reality that the two places you'll most often find Harry Potter in a bookstore are the Kids section in it's colourful "children's" format, and then stashed in the straight up Fiction section in it's more subdued "Adult" skin; not in the Fantasy section either.
These kinds of shelving decisions largely come down to targeted re-branding designed to avoid the social stigmas attached to Fantasy and Science Fiction as genres - especially amongst Youth where simply reading is a good way to end up mocked as a nerd before you get caught with something "geeky". Now, if the store says it's Paranormal Romance... well... you're not reading one of those skeevy Fantasy books that oddball girl or the boys like are you? You're reading Romance. With Vampires. There's an entirely other set of social stigmas assigned to Romance as a genre, admittedly, but most of those don't get applied until you're 30, have 12 cats, and no romantic options are forthcoming. For teen girls who need to be fed up a bunch of completely unrealistic parent-pleasing expectations about how relationships work they're A-OK! Especially since teen Fabio never makes a play for or gets in your panties.
After all, you've got to be 18 before you're fit for Harlequin. And Married.