To Dare a Duchess by Tamara Gill

After five long years trapped in the country, newly widowed Nina Granville, Duchess of Exeter, has returned to town to start over. But it was here she committed an indiscretion—one stolen night of pleasure—that would threaten all she holds dear if revealed.
Byron always loved Nina from afar—until the house party that turned his world upside down. Guilt saw him flee England’s shores, and Nina wed to a man old enough to be her grandfather, but now the handsome rogue is back…and ready to claim what is his.
Yet Nina has kept a secret from Byron, one that could threaten their sizzling attraction and sever their longstanding friendship forever. With Byron’s brother determined to reveal the truth, Nina must use her power in the ton to ensure her secret is kept safe. Even at the expense of love…