. This is only revealed way late into the webnovel. It hasn't been adapted to LN yet, but if it were, it would be about LN 25 or so. The webnovel is way ahead of the light novel
I love how someone basically called Fran a psychopath to her face. The depiction of the evil god communion was interesting, though I can't help but be reminded of the lolicon crying emoji.
For the record, the 18+ doujin does show that while they are still sex friends, the girl is warming up to him. Will he fix her? ... Eh, that's probably over optimistic
... Well that was fast, but not too surprising. The more surprising thing is that the mangaka made a doujin about it. Eh, sure, I can spare a few bucks.
Climax of volume 10 will likely be Kyoutaro initiating the kiss. There's a decent chance the story will end at volume 12, so that means the climax of volume 11 might just be ... THAT.
Great, not only is he a demon lord, he'll be treated as a lolicon if he tries to interact with his lover. History will remember him as Legendary Lolicon Demon Lord Ain.