There once was a king by the name of Arthur, he was the song of the previous king but he he became king because pulled a sword out of a rock. Sounding familiar now. The story Le morte d’arthur talks about his demise. Which was by the betrayal of those closest to him.
King Arthur’s best knight, Launcelot, fell in love with the queen and an affair arose. The king felt betrayed and wanted to have the queen burned at the stake. Launcelot saves the queen. Causing conflict since the King loves both so dearly
King Arthur’s son, Mordrid, wanted to be king. So Arthur goes away to battle Mordrid betrays Arthur by convincing everyone that Arthur has died in battle so he can inherit the crown.
When King Arthur returns, he battles Mordrid regain the crown of king. In the battle, King Arthur dies and mordrid was mortally wounded. Thus killing eachother with no one to reign.
A side knight by the name of Gawain stands up for King Arthur and challenges Launcelot to duel/battle. This happened three times. Gawain lost every time. Until it reached his ultimate demise. King Arthur’s body was sent down a river called the isle of Avalon, never to be seen again.
There are a number of themes such as trust. Trust was shown in the king when he trusted in Launcelot with his army and friendship; along with his wife Guinevere. Another theme is betrayal when the queen and Launcelot has the affair betraying the king and his trust. Same could be used for the themes of deception and love.