Bisexuality was far from uncommon at the French court (as well at many other courts) but it was frowned upon. This did not - however - stop a ménage à trois that involved purely aristocrats!
One of them was Guy Armand de Gramont, the Comte de Guiche, who was already infamous for being a "playboy" with very good looks. He was also a bisexual and caused a scandal at the French court - quite an achievement considering what went on behind the closed doors of the château.
Guy Armand de Gramond had an affair with Philippe I, Duc d'Orlèans but what made it a scandal was that Guy also had an affair with Philippe's wife, Henrietta!
Apparently, Henrietta had begun her affair with Guy Armand early into her marriage with Philippe who was definitely not pleased that his wife was having an affair with his own ex-lover. He became extremely jealous of Henrietta and complained to Queen Anne of Austria. It was even questioned whether the daughter that Henrietta gave birth to after the marriage was actually Philippe's child - it was suggested that Guy Armand was the biological father of the infant girl. One can only imagine what that did to their marriage.