This chapter stung in a million ways I couldn't imagine it would, at first I thought it was going to be a scene I had seen in a million different liar revealed type plots where the main character offends the side character when they say something they shouldn't have, but then she just calmly accepted everything he said. Then the rest of the chapter happens. It's like a rollercoaster where they make you expect a drop, but then it doesn't drop and you think it'll be fine, THEN THE PERSON SITTING NEXT TO YOU PICKS YOU UP AND THROWS YOU OFF THE ROLLERCOASTER! This plays with reader expectations so well that I can't even be mad, masterclass level writing right here.
While I wouldn't call this much of a flaw, as it's something that comes with almost all works of fiction and the shock of the situation will distract most readers from this, the idea that Himeno was able to treat the protag the same way she always did with the same sarcastic quips and even adding in genuine looking romantic interest for the entire time she hated him even leading up to her suicide is pretty unbelievable. Really depressingly poetic that his outburst and her spite is what saved her though...