KOUSHAKU SHISOKU NO SHUUCHAKU KARA NIGERARE SOUNINAI NODE, NIGENAI KOTO NI SHIMASHITA

Fleur, the daughter of a baron, has been plagued by the advances of Victor, the son of a duke and a genius at magic, ever since he proposed to her as a child. So she tries to retaliate against him, which embarrasses her, but... it ends up making him happy, saying, "I'm so glad you think of me that much!" (Source: Kadokawa, translated) — Description from AniList community (anilist.co).