Marie-Antoinette and Fersen
Elena at Tea at Trianon has a post on the nature of the relationship between the Queen and Hans Axel von Fersen. Were they lovers? There has been endless speculation on that point, but I agree with Elena that there is simply no evidence of it. It would have been out of character for Marie-Antoinette, and Fersen was engaged in a torrid sexual liaison with another woman during the years that preceded the Revolution.
What is ascertained is that he was utterly devoted to Marie-Antoinette, and was the mastermind of the disastrous flight of the royal family to Varennes in 1791. He came back to Paris the following year, at great personal risk, to visit the King and Queen and discuss other possible flight plans. None were implemented.
Horribly, Fersen met the end he dreaded for Marie-Antoinette: years later, in 1810, he was dragged from his carriage and torn to pieces by a lynch mob in his native Stockholm. During the State funeral of the heir to the Swedish throne, the crowd accused him of having poisoned the young prince, who had in fact died from a stroke. The troops attending the procession made no efforts to save him.