Prisoner of the Tower: Harlequin comics

It's the social season, and 17 year old Emma heads to London, with her family's hope of finding a rich husband weighing heavily on her shoulders. One night, a mysterious man approaches her. A refined handsome face, curly black hair and deep blue eyes... Emma falls in love at first sight and shares with him her first kiss. 12 years later and now a widow, Emma visits the Earl of Greyston to discuss the marriage of her stepdaughter. It is the Earl's younger brother who is betrothed to her stepdaughter, but the Earl never shows himself. While staying there, Emma spots the man she kissed all those years ago in a portrait on the wall...!