Reddit mentions of Colters' Woman (Colters' Legacy Book 1)

If you want an example of what kinds of books could fall into contemporary romance, check out "Colters' Woman" by Maya Banks.

I don't consider it a particularly shining example of a good story, but it's by a bestselling NY author who's been around a while and is most certainly categorized as mainstream. But it was published in 2006, well before the FSoG craze and was accepted in the mainstream category even then.

While it's light on character development, it's definitely heavy on sex (it's a four-way menage - one woman, with three brothers and they are constantly fucking) and has a romantic arc. This one is actually fairly tame compared to a lot of the newer indie published books available. There's TONS more great sexy romance out there now that indies are taking over so there's no shortage of great romance to read besides this one.