Late reply, but on the brothel management, it isn't ntr because you don't really have a relationship with the girl.
Dohna Dohna is the most recent example i can think to exemplify this. You literally make prostitutes out of girls to, in the context of the game, get resources to lead an revolution against a corrupt elite. You can have sex with them as well, but that's not really a relationship. You're just using them for pleasure.
Even the Rance x Sill relationship is better than that. Despite her being his slave, he really does love her, but he's a tsundere. That is proven by how the story unfolds, but i won't spoil it.
The "i love her, so i'd like to see her banged by however many dudes" is just another way to use her for your pleasure, assuming that makes you aroused.
