Who Said We Were Engaged?

Coralie has spent years supporting her noble fiancé Abel, believing that if she worked hard enough, he would eventually appreciate her. Instead, Abel constantly belittles her and treats her as someone beneath him. Although she possesses extraordinary magical power, circumstances prevent others from recognizing her true abilities. As a result, she becomes the target of ridicule within the academy while Abel offers little support. After one particularly hurtful comment from him, Coralie reaches her limit. She decides to stop sacrificing herself for a man who doesn't value her and begins pursuing her own happiness. Once she starts shining on her own, however, Abel suddenly realizes what he is losing and becomes increasingly fixated on her. The story centers on a heroine reclaiming her confidence while her formerly dismissive fiancé experiences growing regret as she moves beyond him.

https://www.cmoa.jp/title/345342