@theilikepie
The one who was being "bullied" at the start Marie, who's basically a very low ranking noble, and even then by girls because of her attitude and manner. The Duke's daughter, Angelica, the rival, was simply being given the cold shoulder by the royals, which the lower ranking nobility are gossiping about. When the ball came around though, with such a public admonishment and impending social destruction, all the nobles were safe enough in their anonymity and her lack of ability to do anything to them that they decided to kick the dog. As to the royals... they're royals, they have some leeway due to their standing, and Angelica's station far as we've seen hinges on her engagement with one of them.
Unless you're talking about something else, but for now I'm seeing fairly believable situations considering the setting.
Edit: One thing I found odd though was that the MC lost to that guy, considering his training and the fact that he actually did have to fight to survive... He shouldn't have been that easy to roll over.