The Duke and the Matchmaker by Patricia Haverton

“Loving you is a mistake. The most wonderful mistake I ever made.”

Marina is willing to do anything for her twin brother. Forsaking her own prospects to help him get closer to the lady he loves, she will even tolerate one of the most insufferable, snobbish dukes to achieve that goal.
Duke Joseph may be a genius when it comes to business, but he cannot understand people. So when he finds himself engaged to wonderful Lady Florentia, a woman he has absolutely no chemistry with, he is at a loss. Until a fiery, pushy, and beautiful young lady approaches him with a most peculiar plan, that just might work!
While they are playing Cupid, they fall victim to his charms themselves. Just as Marina is finally ready to admit her feelings for him, Joseph receives a threat: Marry Florentia or the whole ton will know your family’s deep dark secret!