The Devil in the Saddle By Julia London.
No one cheats on a Prince and gets away with it. And Hallie--Texas socialite, would-be ballerina, and the only daughter of the renowned Prince family--is ready to give her two-timing fiancé a piece of her mind. But fate plants hot, sexy ranch hand and ex-Army Ranger Rafael Fontana quite literally in her way. Her childhood friend is all grown up. He's sexy, he's handsome, and suddenly, after all these years, Hallie is taking notice. Rafe has been in love with Hallie since they were kids, but he was always the help--and she was glamorous and popular, seemingly off-limits to a lowly cowboy. But now he's back at Three Rivers Ranch to help his family and Hallie is there too--and she needs his support. Soon long-buried feelings boil to the surface, and the desire between them is hot and palpable and undeniable. Rafe realizes he wants Hallie--and her adorable puppy--for keeps... he just has to convince her to give true love another shot."--Publisher's description.