Vincent Pennsbury, the thirteenth Duke of Fallshire, has very specific rules for his imminent marriage: No sex, and absolutely no falling in love. It will be a strictly business arrangement: Higher status for his spouse, and someone who can manage his financial affairs for him, Vincent having no head for numbers. He has no intention of either tumbling his spouse into bed, or of falling in love with them. Choosing Matsui Eiji, a math-inclined widower and the most beautiful man in town, is a therefore bit of a risk. Vincent and Eiji manage to keep their hands off each other for a few weeks, but soon enough they're falling—first into Vincent's bed, and then, to Vincent's horror, into love. When he finds himself mired in deeper feelings than he'd ever anticipated, he panics and makes a terrible mistake. Will he be able to fix it and win his husband's heart back? And does he even want to?