What happens to lancelot and guinevre after King Arthur dies?

Answer 1

There are no easy, quick fix answers when dealing with Arthurian literature and the Arthurian legend. In general, Guinevere goes to a convent at some point before Arthur's final battle at Camlann against Modred: it depends on which version you're reading. In some versions, Modred falsely proclaims that Arthur is dead and tries to marry Guinevere. There is one version where she actually does wed Modred. But mostly she resists him and winds up in the convent.

Lancelot is said to try to help Arthur in the final battle against Modred at Camlann, only coming too late. He then goes to Guinevere in her convent and tries to kiss her, even for one last time. But she remains true to her new vow as a nun and is truly repentant for her love of Lancelot. She refuses his kiss. Lancelot goes off and becomes a priest. Sometime later, Lancelot has an urge to visit Guinevere one last time and goes to the convent, only to be told that she had died a short time before his arrival.

So Lancelot takes Guinevere's body to be buried with Arthur. And not long after this, Lancelot himself dies.