TITLE: REALLY Bad Timing, Apparently
I hope it's clear in panel two that the "BRIIING!" is the school bell, meaning they're supposed to be getting to their classes now (to be precise, they have six minutes before they're late).
While I don't enjoy writing arguments like this, I do enjoy creating scenarios where both characters have valid points. I don't believe there is any way to look at this where one character is entirely at fault here short of being biased towards that character.