There really was an actual King Arthur according to historians. Most recently the theory goes that King Arthur was actually one of the last Roman’s on Britain who rallied the mixed Roman and Briton natives to the cause of defense against what was most likely a Saxon threat coming across the waters when Briton was abandoned to it’s fate.
Late in the empire’s history the empire was under attack from many different directions by invading barbarians. In order to cut losses and make the boundaries more defensible the emperor abandoned Briton it it’s fate and all who were there. At the time there were still a legion based there with it’s commander. This commander is believed to be the same Artorius who’s name and inscription were found among Roman stone there. They believe the historical Camelot was where he had based his hill fort to make his stand. Among his knights were very likely Sarmatian mercenaries from far distant Sarmatae. These were superb horse archers who excelled at cavalry actions. It is believed that seeing that everyone’s fate was the same if they did not stand together this Roman general made peace and an alliance with the natives and even the druids of whom the mythical Merlin is believed to have belonged. The beautiful queen Guinevere was very likely a aristocratic Lady or possibly a Briton princess. The most likely is that she was a local princess who the King took to wife as part of the alliance.
The Sex involved with Sir Lancelot may have been Sex between one his Sarmatian officers or another Roman officer. It is very possible then that most of the details concerning the myth were in fact true and the myths themselves were the oral accounts passed down through the generations. As it was King Arthur and his men were more than a match for their foes and threw off the Saxon threat and the singles among the men took wives and lived on.