Because they wont have the drive to actually change their goal. Hell, I'm certain that if she'd have forced herself to not fall for him or just hate his ass for being a thot and changed her goal to running away and becoming a pirate or razing the house as she left then her fiancé would have pulled the "interdastin" card and been all over her like a the thirsty boy he is. Stories like this are just suffering porn if you don't actually pull off the happy ending the first time, or ever.