Damn, if you only read this chapter, the King really look likes a villain..
Nah, he only sent him to the border, but that fiance's family got rich while orphans and widows were getting deprived of support! So, if that fiance and his family were cunning enough to do that without a troubled conscience, they can also come up with measures to ensure nothing too bad happens to the son at the border (like, by sending an impostor in his place, for example).
I mean, what he wants from tsubasa. Yes, she's wrong for forcing Yuu to be in relationships with Natsume. But in the end, she's hurt too from the accident.
If he wants Tsubasa to apologize, then tell her. Don't traumatized her like she's some kind of criminal.