The Incorrigible Mr. Lumley - The Bridgethorpe Brides, #2

Stubborn. Hard-headed. Single-minded. The qualities that make David Lumley a successful horse breeder are put to work befriending Lady Joanna Hurst with less than noble intentions. He's tenacious in his pursuit of the answers he seeks. Lady Joanna falls fast and hard for the handsome, witty and charming Mr. Lumley after her brother's ultimatum to find a husband by the end of the Season. He is everything she imagined a husband could be, and more.
Blissfully unaware of the conflict between their fathers, she believes he'll declare his love soon. Then she overhears a conversation between Mr. Lumley and her brother, and all of Mr. Lumley's tenacity will be needed if he's to win back her heart.