Not Quite A Lady — Loretta Chase

IRRESISTIBLE FORCE
Darius Carsington is a spectacularly handsome rake with a rare intelligence and no heart, a man who divides his time between bedding loose-moraled women and writing scholarly papers. He finds society's "perfect darlings" exceedingly boring. But there's something intriguing, and not quite perfect, about faultless Lady Charlotte Hayward. He senses a crack under her polished surface, and finding it is a challenge he can't resist.

IMMOVABLE OBJECT
Lady Charlotte is so beautiful, charming, and gracious that no one has noticed what an expert she is at Not Getting Married. Early on, she learned a painful lesson about trust...and temptation. In the years since, she's devoted her life to being all she ought to be -- and she's not about to let a man like Carsington entice her to do everything she shouldn't.

A SPLENDID COLLISION
But the rules of attraction can easily overpower the rules of manners and morals, and sometimes even the best-behaved girl has to follow her instincts, even if it means risking it all.