Yun Yi Yi is 13 years old and accused Chu Fei Yang of ruining her because of well... reasons that the author needed. (*insert overused excuse that people in the past like YYY age differently* No, there's no proof of that. There never has been.) Yun Yi Yi was clearly marked as a spoiled girl from the start, of course, she was going to try and ruin his reputation for reasons that the author decided willy nilly.
As revenge, our supposed "hero", Chu Fei Yang, has her marry her rapist, and her rapist takes full advantage of it. Chu Fei isn't a saint, I understand that, but the thing that made him believable was his levelheadedness. He knew who the real targets were. Aka not some 13-year-old with a petty vendetta and a half-baked plot that didn't work out.
The argument that could have been made was that to get revenge on Yun Yi Yi's father, CFY had to sacrifice Yun Yi Yi. But the author makes it clear that YYY's father doesn't care for anything other than his reputation. Both daughter and father could have easily have been exiled.