The central theme of this novel is that a young person in love must weigh the feelings in her heart against the prudent advice of a trusted elder. The message is that love matters, and one must trust oneself.
The young Anne Eliot makes a mistake in not fully trusting in her feelings for Frederick Wentworth. She wants to marry him. They are both in love. But her aunt, Lady Russell, persuades Anne to break off the marriage engagement. Wentworth's economic prospects are uncertain, and Lady Russell fears Anne will end up poor and full of regrets if she marries him, especially if he is unsuccessful in his naval career.
Anne follows her aunt's advice but lives to regret it deeply. She did not pay enough attention to her own feelings. Because she loves Wentworth, she turns down a marriage proposal from the well-off Charles Musgrove, who ends up marrying her older sister. She becomes, by 26, a marginalized spinster who nobody treats as important. When Wentworth returns to the neighborhood a wealthy and successful captain, Anne has every reason to believe she should not have allowed her aunt to persuade her break the engagement.
This is perhaps the most Romantic and autumnal (full of regrets for times past) of Austen's novels. In all her novels, she shows the plight of women on the marriage market with little money, who are torn between economic prudence and love. In this novel, true love wins out and is united with money, but not until after many years have been wasted when Anne and Wentworth could have been together.