Mushoku Tensei: Jobless Reincarnation (Manga), Vol. 18

Rudeus is enjoying every moment of his newlywed life with his beloved wife Sylphie. However, there is one other person at the University who remembers life on Earth - Nanahoshi. While Rudeus has much to love in his new world, Nanahoshi desperately wants to go back home. She's designed a huge magic circle meant to bridge the gap between worlds, but when the experiment goes wrong, it creates a dire crisis of confidence that only Rudeus can set to rights.