The Italian's Rightful Bride: Harlequin comics

Joanna, an archaeologist, visits the palace of the Duke of Mantejano to research the fifteen-million-year-old crumbling castle. The current property owner used to be her fiancé, Gustavo Montejano, and her first love. She broke off the engagement with him as he loved someone else, and wished him happiness and hid her love for him. Gustavo, who she believed led a happy life, is facing loneliness because of troublesome relationships with his ex-wife and daughter. Joanna is unable to refuse his cry for help…!