Final answer:
Leita's sadness is attributed to her prolonged separation from Wynne and leading a monotonous life, which has led her to a state of deep loneliness and contemplation.
Step-by-step explanation:
Leita spent her time away from Mr. Peters immersed in isolation and reflection, which contributed to her sadness. Without the company of Wynne and immersed in a routine of work, she felt a deep sense of loneliness and lack of direction.
Her situation is echoed in the experiences of other characters who similarly struggle with feelings of solitude and longing for different life circumstances. The passages suggest that Leita's sadness stems from her separation from Wynne and the monotonous life she leads as a result. Additionally, a reflection on past choices and the present stark lifestyle contribute to the melancholy mood.