It looks like it didn't end yet. I didn't get the fulll story but it feels similar to Katsura Airi's Karami Zakari.
Base +6, ehlla +6
Posted on 21 December 2019, 15:02 UTC by: ExtremeRampage
Score +47
Hm? My comment got deleted, weird.
Anyways what I previously commented and "bergil" also pointed this out is that this story, without understanding the dialogue, seems very similar to "Karami Zakari" (which even has a real-life porn version lol) whereby the MC and his crush get dragged into swinging and has to watch his crush getting screwed.
There is also another Hentai called "Chitose" with a similar concept. Seems to me that this might be a new Trend in NTR.