can someone help me out with the plot, ima bit confused...

Dunno if I should be replying to such an old comment, but oh well!
So, it starts where most fantasy stories end, with the defeat of the demon king, but instead of slaying him, the FL gives him a second chance to be ‘human’. During his recuperation and rehabilitation he falls in love with her, she reciprocates, they get married, have a kid, the end. Happy Ending. If he’d won as the demon lord, he never would’ve gotten that wonderful life he’s living.