Akugyaku Seijo desu ga, Aisuru Dannasama no Oyaku ni Tachitai desu. (To wa Ie, Kirawareteiru no desu ga)

When Charlotte awakens, she discovers she has amnesia. The power that earned her the title "Peerless Saintess" has been sealed away, but that's a trifling problem. What matters is her husband, Oswald, is just too cool! However, it seems he hates her terribly, because Charlotte's cruel behavior in the past had caused people to suffer. If so, then she'll do her best to hide her amnesia and be of use to him! It's a heart-warming love fantasy woven by a cruel saintess who's smitten by her husband, the clumsy genius mage.

(Source: Ichijinsha, translated)