Okay, so MC's mom was looking for a casual hookup(already not good for a harem/incest game), met some guy and went to his home with him, and thought it was alright when he shared his BDSM kink, and allowed him to lock her up in the dungeon waiting for sex. Nothing really happened so it's not NTR, but that scene was supposed to be funny? I'm sorry but i don't see it. It was actually sad to see that MC's mom is so desperate that she would let a man she just met at a bar lock her up in some BDSM dungeon and make her crawl like a fucking dog, after that i lost all my interest in her, and you can't avoid doing things with her either.
When she wakes up with mc's dick in her mouth she thinks to herself "why couldn't this have happened with guy from yesterday?" so while she's with the MC, she's actively thinking about the other guy and what could have been

. And now we got the classic sister becoming stripper trope. Which certainly will generate more almost NTR but not really scenarios. Harem is a planned tag, i wonder when we're gonna get to that, right now this looks like it's one bad update away from turning into cuck-fest