It has been a long time.
It has been too long, too long since King Arthur was lost. Truth be told, Lancelot had not expected King Arthur to make such a promise.
Among countless women, he fell in love with each one he encountered, but the queen was special to him. In the course of their love affair, the only physical contact he had with Guinevere was an unintentional brush of their fingertips, and their love remained at a spiritual level.
Not just remained.
Theirs was a relationship so pure that it needed no other actions to prove it. He was caught in the web of love and could not escape. Lancelot was easily moved, but Guinevere...
Guinevere had an irresistible charm to him.
"She has a breathtaking allure, and anyone who sees her will be moved." - This was a fact recognized by everyone.