So I got it a bit wrong, this was halfway through the source material. Not that it makes it much better. The author seems to have just given up after not knowing what to do with it
In the web novel this was pretty much just the prologue, I remember it being only a few chapters into the story. The manga slowed the pacing by a lot.
The author abandoned it after the first arc though, in which he went to the capital and fought a demon lord again. This is a better ending...
The human girl is kinda really dumb here. She created a robot with human level intelligence and emotions, made its sole purpose be loving her, and then decided to cheat on her. It would have been surprising if this hadn't gone south
The mc really really needs to stop with the constant pay up or be kicked out lines. He could show some consideration for what they have gone through atleast