The marriage arrangement

Kole Asher the good looking soon to be prince of Botnia has to choose his wife soon. On a whim he runs into a girl on the street, he thinks she's beautiful and decides hes going to marry her. Sienna Violet was a normal girl until she met him now she's expected to marry him and not say anything about it. They're only teenagers and are expected to run a country in a few years.
His family paid off hers so she's now living in the castle and has to stay in his room. She's determined to convince him to get rid of her, but he's determined to keep her. But when threats from an anonymous person who says they want the thrown start appearing Kole fears for Sienna's safety.
Can Sienna go back to her old life? Or will she endure a horrid arranged marriage.
Will Kole get her to fall for him? Or will he set her free?
What really happens in a marriage arrangement?