When lancelot commits adultery with queen guinevere what does he violate?

When Lancelot commits adultery with Queen Guinevere, he violates the chivalric code, which emphasizes loyalty, honor, and fidelity, especially to one's king and sworn oaths. His actions not only betray King Arthur, Guinevere's husband, but also disrupt the ideals of knightly conduct and loyalty that underpin the Arthurian legends. This betrayal ultimately leads to tragic consequences for all involved, highlighting the conflict between personal desire and societal duty.