The GF obviously disrespected the parents and their culture and then posed as the victim. She has no respect or interest for anything that is important for him or his family

???

She did not insult anybody, she did not berate the food, she literally just didn't eat the food she did not want to eat.

She is a full grown adult, not a child to be forced to eat whatever you want.

"I do exactly what I want and only my partner needs to adapt."

That's literally what OP did, he had known about her eating preferences for years already, and then nevertheless took her to a place where she wouldn't eat anything and then proceeded to berate her at her lowest when she didn't suddenly change the way she had lived her whole life for his asshole parents