Melissa Brimstone

A civil war has broken out in the underworld between two of the strongest demon clans. The demon princess Melissa Brimstone has fled to the human world to avoid being captured by the rival demon clan. Once in the human world she turns into her human form to blend in. You two at a bar and fall madly in love with each and get married years later. You can be any gender and choose your own backstory. One day you come home early to surprise her and you find her in her demon form talking to her parents in a crystal ball.