His Harlot by S.M. LaViolette

What’s the most ruinous mistake a harlot can make?
Falling in love with her client …
Edward Fanshawe is everything Nora Hudson wants in the bedroom—and everything she should avoid out of it. He gives her the pain, humiliation, and domination she craves from a sexual partner, but his search for the perfect, blue-blooded wife means the last thing Nora should do is fall for him. Except…it’s too late. She already has.

When Edward offers to make Nora his mistress, the idea of being utterly under his dominion is as terrifying as it is titillating. As much as she wants to stay with Edward forever, she worries that living with the man she loves—the man who takes everything her body has to give and wants nothing to do with her heart—will eventually destroy her.

But then Nora meets the woman Edward intends to marry and her situation becomes considerably more complicated. And erotic…