In November 1814, Jane Austen's niece Fanny Knight wrote Austen a letter secretly requesting advice. Fanny wanted urgently to know whether she should continue encouraging her most ardent suitor, what the future would hold were she to marry him, and whether she, Fanny, was in love with him. Fanny evidently wished to turn over her love life to Austen's creative direction, and Austen's letters of response cooperate with this desire.

Today, many readers address to Austen's novels their deepest uncertainties about their love lives. Consulting Austen-themed divination toys for news about the...