Who decided that the Saint had to become the Crown Prince's fiancée? I find it painful to be constantly told by my younger sister that it's unfair that she was able to become a fiancée just by being the Saint. And now His Highness has consulted with me about wanting to break off the engagement because he has someone he loves.

Following the custom that the Holy Maiden becomes the Crown Prince's fiancée, I became His Highness's fiancée. However, it seems he has someone else he cares for, and I am treated poorly. On top of that, my younger sister, who sneakily takes my things and complains that it's unfair, keeps saying things like "unfair" about the Holy Maiden and being the Crown Prince's fiancée, which has become annoying. So I decided to investigate this custom about the Holy Maiden becoming the Crown Prince's fiancée.