Lola Brown is five years old and is from Finaghy in Belfast.
On Friday, her primary school held a royal tea party at which she got to dress up as a princess, but she expected a lot more than just that.
While making the dinner on Friday evening, her mother Ashlee broke the news that she would not be going to the Royal Wedding at Windsor Castle the following day.
Sharing the video on Facebook, Ashlee wrote:
"As I was making dinner, Lola asked me 'Mum is my dress for Megans wedding in London or are we going to pick it up on the way to the airport to go to London', that's when I realised she believed she was actually going to the Royal wedding."
Here is the heartbreaking moment she realised she wasn't invited to Harry and Meghan's bif day: