Hello is it true that Elizabeth called Richard her "only joy in the world?"
I believe that is a line out of The Buck Letter. The Buck Letter is considered a document which cannot be relied upon, because it’s origins and the circumstances of it’s writing cannot be verified.
The Buck Letter was a supposed copy of a letter from Elizabeth of York to the Duke of Norfolk. The original letter itself has long since been lost, but George Buck, an antiquarian of King James 1 claims to have seen the letter in the private collection of the Earl of Arundel (probably sometime around 1600). Buck copied down the letter from memory, which doesn’t seem all that reliable.
George Buck’s copy of the letter survived long after the original was gone, however Buck’s letter sustained major damage from a fire during the 18th C, and parts of it are missing or illegible.
Here is what we have left of George Buck’s copy from memory of Elizabeth of York’s letter:
“…st she thanked him for his many Curtesies and friendly
in the cause of…
and then she prayed him to be a mediator for her to the K…
ge who (as she wrote) was her onely joy and maker in…
Worlde, and that she was his…harte, in thoughts, in…and in all, and then she intimated that the better halfe of Ffe…was paste, and that she feared the Queene would neu.…”
Not exactly the evidence you want to be relying on to support the widely discredited theory that Elizabeth of York had romantic feelings for her uncle, eh?
From this George Buck’s great nephew (also, confusingly, called George Buck) attempted to reconstruct his great uncle’s copy of the letter. We aren’t sure what enabled him to make this reconstruction of the letter, had he seen or copied his great uncle’s letter prior to the fire damage? That’s not able to be answered.
In short, my answer to your question is, I don’t know if Elizabeth of York ever referred to her uncle that way, but the evidence we have that she did is extremely unreliable.
Thank you for the ask.