Bertie's perspective, as revealed by the details in the passage, suggests he is somewhat perplexed and concerned about the situation at Easeby, especially regarding his Uncle Willoughby, who is depicted as a serious and quiet man engrossed in his writing. While the options provided do not directly align with specific statements from the passage, the implication is that Bertie is wary of Florence's plans, as they cause him to question her motives and feel uneasy about their relationship.
Among the options given, the most fitting response that captures Bertie's ambiguous feelings towards Florence and his uncle's work is:
He loses interest in marrying Florence once he hears her plans for Uncle Willoughby’s manuscript.
This choice aligns best with his overall sense of concern and confusion about the family dynamics and potential conflicts between him and Florence regarding her intentions.