I know it's on purpose but the mere idea that this is even a realistic, possible bad ending is kinda sickening ngl. It doesn't even track with the kind of people Tsumugi and Itoshi are.
It might be the most yandere the MC has been the whole manga, it's pretty interesting. I'm glad it's just a what if scenario though, there's no way FMC would have kept having sex like that.
I'm mostly just sad because this makes it clear the manga is ending soon.