I thought I was here to cum, but now that I'm here, I cry ;_; I can't believe I'm saying this, but fuck me, I would have preferred this to be 'just' a straightforward NTR story.
@Mr. Ghost it is a callback to page 4 where she is (effectively) apologizing for not being good enough, thus requiring Rinko to go through extra effort for her sake.
"it is a callback to page 4 where she is (effectively) apologizing for not being good enough, thus requiring Rinko to go through extra effort for her sake."
Should have known that was the implication since it's implied that company owner showed the video he made of him having sex with Rinko to Satsuki. A very bleak ending indeed.