I read this again and I feel it's pretty bittersweet. Both Asama and Satsuki are thinking the relationship can't last. Satsuki knew this from the start and yet she still went through with it. It's almost tragic, but this story doesn't go there.
...Well, she's definitely quite an understanding sister, and at least he seems to be taking some responsibility for what he did...
Or rather, since she also liked him to begin with, being a responsible Hentai Protagonist and taking care of them both.
Still, I assume this is a part 2 or something of a previous chapter(Considering the 'again' part of the title), so I'd definitely like to see that, too.
Or rather, I've not been paying attention to all the triple dots. Because when reading on a phone and seeing icons to indicate '< My Lover' and 'Her Little Sister>', I auto-zoned into the idea that it was just identifying who is who. So the sentence '... and I all decided...' turned into 'And I all decided...' in my head.
Real blunder on my part though, thanks for correcting me. But then again, that remark after that was not needed.