I realise this is a ridiculous thing to be arguing about but interested in opinions of whose in the wrong here.
A orders the food shop to come 10-11am. B is working at home at that time. A expects to be home by 10 but ends up running late by 15 minutes. The shop arrives at 10am and B has to take it in and put the frozen things away. A puts the rest away. A says they would have messaged B that the shop was coming but normally this supermarket sends a text 15 mins before they arrive and they didn't this time. B thinks A was inconsiderate not to let them know the shop might come before they were home.
A and B are now in a stand off as B won't let it go until A apologises for being inconsiderate and A doesn't accept that they were inconsiderate.
YABU - A is in the worng
YANBU - B is in the wrong
If you can't tell we're both extremely stubborn.