The Duke's Secret Heir by Sarah Mallory

A wary wife can't resist her own husband in this compelling Regency romance from the award-winning author of The Chaperone's Seduction.
"This, madam, changes everything."
Years ago, in the Egyptian desert, Ellen Tatham fell wildly in love and exchanged vows with Max Colnebrooke. But, when made to believe Max could not be trusted, she fled . . .
Now, Max is back in England to take up the reins as Duke of Rossenhall. And when he spies Ellen at a ball, the sparks are hard to contain. Little does Max know, though, that Ellen has a secret . . . And soon, he must learn to embrace an unexpected heir, and an unexpected—and disconcertingly defiant—duchess!
"Well-written . . . an entertaining, angsty read, and one that should appeal to those who enjoy second-chance romances." —All About Romance