I was once on a flight on UA with facts similar to what AS flyer said. The F FA refused help from a Y FA, when it was certainly needed and available. I heard the offer, heard the refusal, and we had a few hours of marginal service, with a poorly-executed full dinner service. I made mention of this to the FA who had offered later in the flight, and being junior, didn't want to "insist" but also knew that our service was suffering. I can't quite figure this out. "Works well with others" you would think should be a job requirement...