Final answer:
Without a specific text to reference, Guinevere's vexation with a novice could be due to any number of reasons commonly found in Arthurian legends, such as jealousy, betrayal, or disappointment.
Step-by-step explanation:
The question "Why is Guinevere vexed with the novice?" generally seeks an analysis of character motivations within a literary context. Guinevere is a character commonly associated with Arthurian legend, including works of literature that revolve around the mystical Camelot and often involve intricate relationships and emotions. Without specifying a particular text where this scenario takes place, it's challenging to provide a definitive answer.
However, based on the general nature of Guinevere's character in Arthurian tales, reasons for vexation could stem from jealousy, betrayal, disappointment or a breach of expectations that novices, who are typically inexperienced, often incur unknowingly in stories.