Heiress of Misfortune by Ruth Ann Nordin

When Mr. Byron Tumilson was hired to protect Lady Eleanor from the person who is trying to kill her, the last thing he expected was to play the role of her suitor. But, as it turns out, that’s exactly what her father, the Duke of Dormondton, requires him to do. Her father wants her to have a successful first Season, and no one has shown any interest in her. He is convinced that if Byron pretends to be in love with her, then she’ll attract real suitors.
So Byron is stuck attending boring balls and lavish dinner parties under the guise of being a wealthy gentleman. As if that isn’t painful enough, he needs to find a way to make this wallflower of a lady into someone gentlemen will actually desire. At least, that’s what he most wants until Lady Eleanor pretties herself up and learns how to flirt. Then he starts to realize he’s fallen in love with her, and that’s the worst thing a nobody like him could do with a fine noble lady.