Although she's the diamond of the season, Edwina also has the unfortunate fate of being the unwitting third wheel in a love triangle between her suitor Anthony and her sister Kate. In the books, this is all handled fairly casually. While they like one another well enough, Edwina and Anthony's relationship doesn't get all that far before the bee sting incident forces him to abandon the pursuit of Edwina and marry Kate instead.
In the Netflix version, however, things get a lot more dramatic. Desperate to prove himself, Anthony actually proposes to Edwina, and Edwina truly develops feelings for him. They even get as far as the wedding before Edwina realises that she's not the sister he really wants. Edwina calls off the wedding at the alter, and although she's upset with Kate for a time, the sisters reconcile after Kate falls off her horse and is knocked unconscious. When Kate comes to, Edwina encourages her sister to stop living for other people and is supportive of Kate and Anthony's marriage.
The Netflix version even gets the Queen involved in the plot! Seeing an opportunity to get one up on Lady Whistledown, the Queen shocks everyone and announces that she was the one who called off Anthony and Edwina's wedding. She then suggests that Edwina might like to meet her nephew, a prince... sound familiar?