Well, shit. Sad to hear that the dev's got a history of leaving things unfinished. I was pretty stoked to find a game about one of the most famous NTR stories of all time.
It's so funny that the french wrote (most likely out of spite) that Arthur, a british folk hero and a central figure in their early history, was actually a cuck and it became canon.
Oh no, that part gets even better when you keep digging into it.
Chrétien de Troyes, the guy who wrote the version of Lancelot and Guinevere's story that's become the canonical version (and who may or may not have invented the character of Lancelot altogether to make him Guinevere's lover), was under the patronage of Marie of France, Countess of Champagne, who apparently particularly liked his work on the forbidden love of Guinevere/Lancelot.
Marie herself was a Princess of France, and the daughter of King Louis VII and Eleanor of Aquitaine, the latter of whom remarried to Duke Henry of Normandy (who would later become King Henry II of England) after her marriage to her first husband was annulled around the time Marie was 9 or 10. Louis VII kept his two daughters' custody as his ex remarried. Chrétien entered Marie's employ about 15 years after Eleanor had remarried.
So in her mid 20s, Marie paid a guy who wrote fanfiction about an English queen cucking an English king with a French knight. Maybe she felt like her mother was being stolen away going into a loveless marriage by Henry II and wanted a tale about her escaping that (which has some concerning incestuous overtones, but still), maybe it was a romanticization of her Eleanor's marriage history with the nationalities flipped (so, a French queen being seduced by an English duke flipped to be an English queen being seduced by a French knight). Or maybe she herself was self-inserting as Guinevere (she wasn't married yet when Chrétien entered her employ, but she'd already been betrothed to the Count of Champagne for seven years, so she might have been feeling trapped already).
At any rate, the gal was horny for some NTR happening to somebody close to her, and Chrétien was happy to provide.