Gentlemen Prefer Heiresses by Lorraine Heath

Lord Andrew Mabry, the second son of the Duke of Greystone, has no desire to marry. As the spare, he has no obligation to provide an heir and he rather enjoys spending his days and nights in play with the demimonde. But more and more of late, he finds himself wanting to play naughty games with the American heiress, Gina Hammersley.
After her scandalous older sister marries a marquess, Gina Hammersley suddenly finds herself the darling of London with beaux a plenty calling on her, sending flowers, and filling her dance cards. Unfortunately, the one she desires most is the one who has no wish to be caught in the marriage trap: Lord Andrew Mabry.

But when they are discovered in a compromising situation, this unlikely pair must decide whether to face scandal or discover if the passion they’ve always felt is strong enough to lead them into love.