I like how no one (other than the father) is a terrible person.
The prince has his head up his own ass and jumps to conclusions about "justice" too quickly, but he's been called out in it and started reflecting on it. Violet went from another girl constantly trying to win him over to a mature woman who also helps/stands up for her younger sister. A change in his opinion of her is actually understandable. Doesn't mean I'm not rooting for Yulan though.
Prince's friend is just trying to help his buddy out with his love life. He's a bit if an ass about it, but Yulan and Violet technically aren't together so there's nothing wrong with him putting his friend before someone he doesn't care for. And from an outside view, Violet marrying a prince is a definite step up.
Younger sister is the typical naive and kind type. She acts the way she does because she doesn't know better. Once she has things explained to her or sees why things are the way they are she begins to understand. Can't blame her for her father cheating on and abandoning his first wife. Also can't blame her for not knowing things that no one taught her. I really hope there's a scene later where someone explains the family situation. Pretty sure the best revenge on dear old dad is to get his favorite daughter to hate him.