Guilt
"Don't you feel bad?"
Nagisa blinked and looked up. "Eh?" He didn't know the girl standing in front of him; well, didn't know her name, at least. She looked vaguely familiar. "Bad about what?"
"Seducing Tachibana-senpai away from Nanase-senpai," clarified the girl. "Don't you feel bad?"
"Huh? What - no - Haru-chan and Mako-chan are just friends!"
Nagisa had always tried really hard not to be jealous of how close his two oldest friends were. But there was always that niggling doubt -
The girl gave him a pitying look.
Nagisa felt sick for the rest of the afternoon.
Not necessarily connected to the previous chapter, though you could interpret it that way, I guess.
