Sakkon no Cinderella wa Kutsu wo Otosanai. Modern Cinderella Does Not Drop Shoes.

Synopsis

In the middle of a grand ball, my fiancé cancelled the engagement. The reason was... I tried to avoid the cancellation of the engagement, but it wasn't meant to be. An unfortunate pitiful lady and a stubborn general. (Source: Shousetsuka ni Narou, translated)