Final answer:
Darcy's two reasons for not joining in the walk are not directly stated, but his dislike for dancing and concern for societal expectations and judgements could be inferred as possible reasons.
Step-by-step explanation:
Darcy's reasons for not joining in their walk are not explicitly mentioned in the provided text extracts. However, from the context of these passages, we can infer two potential reasons. Firstly, Winterbourne expresses a preference for not dancing and implies a general disinterest in the social norm, which might translate to a reluctance to participate in the walk. Secondly, societal expectations and judgements seem to be a concern for him, as reflected in his conversations about propriety and the appropriateness of Daisy's behavior. Both suggest a character who is mindful of social norms and his own preferences, which could lead to his hesitation to join the walk.