The Duke Useless Bride

Candy Crosshearts is a daughter of a rich count. Her mother was a maid that the count had a affair with. Being a mistress daughter, she was bully by her step mother and step sister. She was locked away and kept unknown from the public. If it was known that the count, her father had a child out of an affair, it would ruin his reputation. If she was born a boy, it would be a different story. Despite being locked away, she still had servants who took care of her like she was a princess. But she received no education or tutors. Raised like a doll but caged up from the dangers of the world. Until one day, her father lose all his fortune due to his gambling. He becomes despair and have sold his daughter to be married to the rumor scary Duke of Archbelo. Her step sister and step mother refused the proposal but what can they do cause the deal was already signed. But wait, they still had Candy to go in place of her step sister. Candy must now get engaged to the duke.
But she is not scared of the Duke as everyone else is. She gets married to the Duke and the Duke finds out it's not her step sister but another daughter of the Count. The Duke is outraged but still makes Candy his bride. Candy having been raised lock away and not receiving etiquette is push to learn everything as a royal. She have to attend balls and socialized with the elites. But nevertheless she works hard to learn of this new world.