She said the food was terrible, and sounds like her initial judgement of them made her stiff and closed off throughout the day. She’s a stranger to them despite three years with the Fiancé which they probably blame on her, but we don’t know why this was actually the case. They sensed that and acted out. They were wrong for that, Fiancé was wrong for not preparing or defending her from them, and she was wrong for coming in with a negative attitude off the bat then storming off dramatically instead of just leaving quietly with humility. If you came from the same background as the Fiancé all of this would be pretty normal, I have similar parts of my own family. Those who have very little are easily offended by someone coming in dressed up, not making an effort to relate to them.