Three weeks with a princess / Vanessa Kelly.

"Lia Kincaid, illegitimate daughter of the Duke of York, comes from a long line of notorious women. Raised by her grandmother, formerly mistress to the late Marquess of Lendale, she has little hope of a respectable marriage. But the new marquess, her childhood friend, Jack Easton, would make a very desirable protector...if he weren't too honorable to take her to bed. It's bad enough being saddled with a title he never desired. Now Jack must resist the beautiful woman he desires far too much. Duty calls, and he is duty-bound to choose a wealthy bride. But then Lia makes another outrageous suggestion: asking Jack to devise some tests to find her the perfect paramour. Tests that involve flirting, kissing, and other pleasurable pursuits. Tests that, in a matter of weeks, could transform friendship into the ton's greatest scandal, igniting a passion even duty can't deny" -- provided by publisher.