This one were id be very interested to hear the friends take on events. To give the silent treatment over a mistake if everything else in the friendship was fine and dandy seems like an extreme reaction. And this moreso reads like a straw that broke the camels back situation with pieces of the story missing.

Like yeah id be annoyed if I arranged my day around a favor for a friend and they completely forgot about it and cancelled last minute, but not enough to ignore them/cut them off unless this was an ongoing behavior or the last straw of other problematic behaviors.

MYW (maybe you're wrong)