Elizabeth didn't fill in a lot of people dear to her very quickly in the end, did she? I know we're discussing the book, but I did take the liberty of rewatching P&P2 this weekend, and I was struck with the incredulity of all those dear to her...
of course Elizabeth had been incredulous about Charlotte and Mr. Collins, but both Jane AND Mr. Bennet are incredulous about Elizabeth and Mr. Darcy. I would think it could be daunting to counteract her strong opinions voiced so very decidedly. But I could see how heartbreaking it might be for her to know her dear sister and father have a sense that maybe she's lost her mind for a moment before she can assure then she hasn't.