Desperately Seeking Scandal by Theresa Romain

Lady Ada Ellis has two great talents: managing the accounts of her horse-mad brother’s dukedom, and hiding in Berkshire from London society. Several years ago, a scandal rag published family secrets—and Ada was jilted as a result.
She has no use for the press or for her onetime fiancé, but fate delivers both into her hands at once. At the same time her former betrothed visits Berkshire with his new bride, charming reporter Colin Goddard seeks Ada’s help for a career-making series of articles on how to snare a wealthy spouse.
Ada agrees to assist Colin—if he acts as her devoted suitor before the man who once spurned her. What was intended as a humorous exploit turns seductive, as she and Colin challenge each other to a battle of wits, wills, and hearts. But Colin is keeping secrets of his own, and if he and Ada fall in love, one of them will lose everything…