In short, they can never be truly together, and the worse her curse gets the more she'll need to satisfy her needs, thus leading to her doing it with other people while he anguishes over it.
This is just NTR.
Fuck this, I'm out. I'm not going to bother reading the other chapters when they'll translated.
(Also, the supply and demand thing was bullshit. That's not how supply and demand works. If the client cannot afford the product, then it cannot be sold, thus meaning that it's a loss. If he thus cannot buy it, it won't be sold. In turns, when things aren't sold, the price lowers. For the price to rise, yes more demand is needed. However, the price still need to be affordable for the ones who will buy it. Otherwise it's just worthless and isn't sold.
I understand that Zepar likely didn't intend to sell it after that point, but the logic used for it was dumb.)
(oh, and I refuse to accept that a demon such as Zepar wouldn't be able to remove a curse of her own making. That's another dumb excuse for a to-be NTR plot.)