For My Lady's Heart — Jane Howard

A MOST DANGEROUS GAME...
They were partners in a thriving London inn, best friends--until nineteen-year-old Katesby Dalton asked Win Beaumarais to give her lessons in love. After all, she reasoned, she'd just received a proposal of marriage from the widowed Earl of Northumberland who wanted a woman of experience, which Kat certainly was not. What Kat couldn't tell Win was that he was the man she loved beyond reason. And his were the fires she was determined to light.
...OF LOVE
Win Beaumarais was a successful man about town. Consequently, he was in no mood to teach an innocent the ways of romance. But then Kat threw him a challenge_to prove his manhood. Now, vowing to rouse her beyond her wildest dreams, he planned to leave her to her fiance's arms, and set out for sea. What Win never reckoned on was the power of passion to haunt his dreams and drive him home again_just in time to find his urchin transformed into a lady, and the flames of jealousy threatening to consume his soul...