Answer:
to illustrate Guenevere’s traditional beliefs
Step-by-step explanation:
The author of this excerpt wished to stereotype the behavior of women in the medieval era, the way he thinks of showing this is illustrating Guenevere's traditional beliefs. Guenever is being unfaithful to her husband, but her beliefs make her worried about her marriage and status as a married woman.
Moreover, it is important to note that Lancelot was not deceiving Guenevere. The couple was not disagreeing and Guenever was not performing any modern behavior.