Francesca Bridgerton falls for a woman in the third series, deviating from the source novels.
Fans of the Regency saga noted the switch when new episodes dropped yesterday.
John Stirling is seen introducing new wife Francesca to his cousin Michaela Stirling, played by Masali Baduza.
She eyes the blushing bride and warns: “I caution you, every sordid detail John has spoken about me is a lie . . . the truth is far worse.”
But in Julia Quinn’s books Francesca — played by newcomer Hannah Dodd, 29 — falls for Michael Stirling after husband John dies.
One fan wrote: “Happy Pride Month to Francesca Bridgerton!”
But another thought it was taking the Michael, adding: “It’s disrespectful to the couple’s fans. They shouldn’t have done it.”
Series three has already had 82 million streams, with the final part featuring a six-minute sex scene.