So I did some research on this game to try and find out what the full lore of this game even is, and although I didn't find much, I did find this image from what I believe to be the first prototype of MIH. Yeah apparently the game was originally an NTR game inspired by Black Souls where you'd play as either a male of a female trying not to get violated by these... things. There's no mentions of either the enemies of protagonists being in a relationship, but it would explain why the protagonist is actively trying to avoid these conventionally hot women. Also because it's implied by the phone guy that letting them get in is dangerous, but who cares about that.
Also Nameless was laterally just the creators way of trolling new players. I'm not even joking, in the walkthrough, the creator says that the Nameless was "a trap for first-time players.", so that's cool.