Sounds like poor organisation and quite a lot of entitlement from the passenger. Even says that the crew gave her some of their lunch!
When booking travel, staff are unable to pass on dietary information to cabin crew. When travelling, it is essential that information on your allergies is communicated to cabin crew upon boarding. Information is available on our flights on the allergens contained within the meals served.

She should have ordered a special meal and she should also have taken some food for herself just in case she was struggling to eat given her dietary needs.