Kono Tabi, Koushaku Ke No Reijou No Konyakusha To Narimashita. Shikashi, Uwasa Dewa Seikaku Ga Waruku, Jussai Mo Toshiue Desu.

Read Manga I Have Become the Fiancé of the Duke’s Daughter. However, According to Rumors, She Has a Bad Personality and Is Ten Years Older Than Me / この度、公爵家の令嬢の婚約者となりました。しかし、噂では性格が悪く、十歳も年上です。

Jared, the eldest son of a Baron family attending the Royal Academy, aims to become a Court Mage like his late mother. One day, after building up a track record through subjugation requests, his grandfather told him of his engagement to Olivier, the daughter of a Duke. Unaware that she is described as “the woman in this country most people don’t want to marry,” Jared visits the Duke’s house and receives a harsh welcome from her. As a result, both express their desire not to marry, but those around them steadily prepare for the wedding. Jared’s classmate Christa and childhood friend Jeni are worried about the situation. In fact, a sinister conspiracy was involved in that engagement…

https://www.cmoa.jp/title/338125/