The Forgotten Duke by Sofi Laporte

When a penniless Viennese musician is told she may be an English duke’s wife, a quest for lost love begins.

Amid the glamour and intrigue of the Congress of Vienna, Lena Arenheim and her musical family perform at aristocratic soirees to make ends meet. When, out of the blue, the sister of the arrogant Duke of Aldingbourne proclaims Lena to be her brother’s long-lost duchess, her safe but small world is turned upside down. Amid opulent ballrooms and echoes of forgotten memories, Lina embarks on a quest to uncover the secrets of her past.
For Julius Stafford-Hill, Duke of Aldingbourne, the wounds of a tragic loss still linger after eight long years. When he encounters a woman who bears an uncanny resemblance to his late wife Catherine, he will do anything to uncover the truth, even if it means immersing himself in her world and facing the everyday challenges of a common middle-class life.