"Kimi wo Aisuru Koto Wanai" to Itta Kouri no Majutsushi-sama no Kataomoi Aite ga, Hensou Shita Watashi Datta

Your husband loves a witch!? "But it's me!!" Fine, the daughter of an earl, is treated coldly by her family. But her true identity is that of the strongest witch, a living legend! She married the handsome next duke, Shion, in an arranged marriage, but he declares, "I'll never love you." She's actually lucky that they don't interfere with each other! But then she rejoices, thinking he loves her, a witch!? A loveless arranged marriage between the strongest "Ice Magician" and the "Witch of Dawn" leads to a blissfully pure, newlywed turmoil!!!!!

(Source: Gangan Online, translated)