The beast that saved Prisana's life was eager to rid of her. That shouldn't come as a surprise. Her presence was only a chess piece in father's and Giovanni's game of power. She's not wanted. She's needed goods. Prisana has been coming to terms with that the entire night of mulling, mulling again, and planning.
When she would deemed as a useless wife and have completed what she was meant to do, both father and Giovanni will rid of her as well. Rid of her by keeping her housed in luxurious mansions grinning happily beside a man who does not love or care for their children.
She would have been content with her happily ever after if not for their betrayal. Running away was spontaneous and unplanned. Meeting him was also spontaneous and unplanned.
