That was...a dark line of thought for punpun. I can't help but pity him while also feel annoyed while also relate lol but c'mon bro, doing cheap gestures just to get sex, no wonder she refused the umbrella at the end. Punpun's self pity is a double-edged sword where he suffers and because of it, expects there's a reward from the universe (or "God") that will come after. Hes done all this, he thinks, he's suffered so much, so why can't he have this? Why not take it when it's denied to him?
Just...unfortunate foreshadowing.