The English Heiress (Royal Dynasty #1)
Roberta Gellis

Roger St. Eyre’s life had been destroyed by the girl he fell passionately in love with. Solange did not love him; she was selfish and vicious and extravagant. By the time she died, Roger felt dead himself. Perhaps he was hoping for the peace death brings when he set out to wrest his old friend Henry de Conyers from the murderous grip of the French Revolution.
Instead Roger and Leonie both found love and reasons to live—if they could escape exposure to the revolutionary fanatics ... and their favorite toy, the guillotine.