"Ah, well, I kinda did something bad to him, and… a girl he likes. Like, really bad. So, he hates me to death for that."
"I mean, I don't blame him, after all, I hurt them in more ways than possible."
In the end, Airi's voice got low to a whisper, which was barely audible to her parents. She recalled how someone she depended on, admired, liked did the same thing to her, causing her harm in the worst way possible. And she definitely feels angry and sad about it, so she understands why this Shiro is hating on her.
