Read the next couple of chapters on the website, and while they reveal that
Caius's relationship with the princess is entirely platonic,
I honestly don't think it matters. No matter how he felt, he never treated Nicole as a priority of his, never took the initiative to make time for her, and took her feelings for granted, all because he was a coward who
didn't know how to treat a lady, so instead of bothering to learn he just ran away from ever interacting with her and chose to retreat to the princess because he could treat Caroline like "one of the boys".
Their relationship was all give no take on Nicole's part, and I'm not surprised in the least she completely lost any feelings she had for him. I know he's probably gonna win her back, but I kinda wish he wouldn't and she would end up completely independent from him.
Also "it's only natural for a lady to attend with her fiance" OH SO NOW YOU CARE ABOUT THAT? BUT WHEN YOU CHOSE TO ATTEND A BALL WHERE LADIES ARE SUPPOSED TO ATTEND WITH THEIR FIANCES WITH CAROLINE AND LEAVE NICOLE BY HERSELF THAT'S FINE? double standard much?