Dirty Sexy Saint (Dirty Sexy 1) by Carly Phillips and  Erika Wilde

Clay Kincaid knows he's more a sinner than a saint. Especially when it comes to women. With a rough and damaged past that has left him jaded, he doesn't do committed relationships.

But he does like sex — the hotter and harder, the better. He likes it fast and filthy, which is why he refuses to even touch someone as sweet and guileless as Samantha Jamieson. Until he discovers that she likes it just as down and dirty as he does. Let the sinning begin...