Escape into The Dauntless Ladies Series by Electra Tanny
John, the Duke of Rutland, was rarely surprised. But one morning, he lay in bed staring at his ceiling, contemplating the most absurd proposal from Oscar, his friend, he had ever heard: 'I want you to sleep with Lydia.'
Never in his wildest dreams would a husband propose, and then thank him for agreeing, to have intercourse with his wife. Not that this was likely to happen. Lydia would never agree to such an arrangement. He was certain a message would promptly arrive from her telling him to stay away and that it was all a sham.
Deep down though, he dared to entertain a wisp of hope; maybe it would be true, the woman of his dreams finally in his arms.