Sora's butting in + forcing her feelings of missing her dead father onto him and it's really annoying. He's free to hate his mom who left him. Especially after he heard what his mom said about the money even if she was being sarcastic.
but its his mothers fault yes what he did was wrong but its just the consequence of his mothers doing sometimes parents are so stubborn and controlling wants to be respected but don't know how to respect their kids either so stupid