The Widow’s Wager by Claire Delacroix

She wed once for duty but will only wed again for love…

For as long as she can remember, Eliza North’s heart has been in the possession of her older brother’s friend, Nicholas Emerson. But Nicholas has always been oblivious to Eliza, and when he bought a commission and sailed to war, she wed sensibly instead. Returned to her brother’s house a widow, she meets Lieutenant Emerson again and realizes neither of their feelings have changed. She accepts his request to chaperone his younger sister, Helena, hoping she might win his attention yet, with the assistance of the mysterious Mrs. Oliver and her guide for seduction.
Nicholas Emerson could never aspire to wed the daughter of a duke, especially one so pragmatic as Eliza has always been. That she married for the whimsy love makes him wonder how well he knew Eliza after all. She is still the only woman who captures his attention, but he knows his injuries mean he can never marry. Still, he cannot resist the chance to request Eliza’s assistance with Helena’s second season, and the chance to share her company.
Neither of them anticipate Helena’s wild behavior or their necessary alliance to defend her reputation. Entrusted with the manuscript of Mrs. Oliver’s advice on the seductive arts, Eliza puts its counsel to use, much to Nicholas’ delighted astonishment. How can he refuse the woman he loves, even knowing that he can never ensure her happiness? Caught between honor and love, Nicholas must accept his legacy from the war for this pair to have a future—is Eliza the woman who can heal his wounds forever?