Kakure Saijo wa Zenzen Megenai: Gibo to Gimai ni Ie wo Oidasareta node Konyaku Haki shite Moraou to Omottara, Shinshi Datta Konyakusha ga Hageshiku Dekiai shite Kuru You ni Narimashita!?

When Jeanette's father suddenly goes missing, her evil stepmother seizes the opportunity to cast her out of the house! Now she's left with no family, no belongings, and nowhere to live. But Jeanette the eternal optimist firmly believes in one thing: "Every crisis is an opportunity for growth!" Eager to face her new life, she has only one thing left to do to break free of her old—call off her engagement with the popular and beloved Count Claus! Little does she know the saintly gentleman she's supposed to marry is secretly a blackhearted schemer, and he has other plans. In fact, he's so madly in love with her, he'll use any means necessary to stay by her side and assist her! Once the couple begins working together, Jeanette's enterprising nature starts to shine. With her positive attitude, her natural genius, and her clever, besotted fiancé, can Jeanette triumph over adversity and earn back what's rightfully hers?

(Source: J-Novel Club)