
Okay I now we all hate the prince and stuff but what if he actually “tested” her?
Back then she told him that she didn’t want to be a noble and live a peaceful life (what she has every right to!!) but being the fiancé of the crown prince things would be difficult to break of.
Looking back at the flashbacks it seems like Schneider actually cared for her.
When the situation with the black haired Heroine popped up he took it as a chance to test her. If he was important enough to Ronia that she would give up on her dream (of leading a peaceful life) and reign by his side as the crown princess or he would let her go, so that she can fulfill her dream.
So Ronia putting herself over the two of them together is seen as a “betrayal”.

That is clever...but also really dumb at the same time, Prince really think that someone like Ronia would give up her dreams, like...she thought leaving him would make him happier...is the way I see it
I don’t whole heartily dislike the idea but shouldn’t the prince go to her to confront her instead of being all sappy and saying she betrayed him
Anyways, I’m not the one to judge
Dude ....