Writing, but don't know where it fits

Ok, new here, so be kind =)

I'm not sure if my hopeful novel would fit into fantasy, or Romance, or possibly something else?

Basic idea:
MC = prostitute
Setting: Feudalistic setting, invented world. No magic, no special powers, but the occassional fantastic creature might make a showing (I'm still debating that).
Basic plot: King dies, younger son inherits, older son rebels.

The MC is really only a marginal player in all this, more of the unremembered hero type of thing (e.g. spends time as Prince's concubine, but works to develope love between him and his wife). In the end, she does not gain wealth, fame, or royalty stauts. It started out as 2 different short stories (school projects), but I've always wanted to put them together and add more about the hinted at sub plots, which will put it well into novel length.

I'm not sure how well this will work out, but I've always wanted to write about the "extras" in the scenes. Sex is kind of necessary to the writing, but I don't want it to become the main point, I'm just not sure if such a plot line would be able to be written as fantasy, or something else.

Thanks!

Thanks much all. The sex is kinda a necessary byproduct. I'm aiming for fantasy, but figured I'd best check with the "masses". =)