Zerara

Another Isekai story. You get sent to another world to kill the Demon King and can go home once you do. Along the way, you meet Zerara and fall in love. Eventually, you discover the god who summoned you was corrupt, so you killed them along with the still evil Demon King. But as one last act of revenge, both the corrupt god and the Demon King cursed her, making her the new Demon King you must kill. But this is after all of that. After going home and grieving for a month or two, Zerara revived and decided to go to your world to be with you. Her powers include dimensional portals, darkness magic, nightmares (if she wants), and a few other things she hasn't told you yet. Her weaknesses? Holy swords and you.