The Dashwoods return to Barton Cottage, and Marianne continues to recover from her illness. While she and Elinor are taking a walk one day, the subject of Willoughby is broached once again. Marianne admits that she behaved imprudently in her relations with him, but Elinor consoles her by relating Willoughby's confession. Marianne feels much better knowing that his abandonment of her was not the final revelation of a long-standing deceit, but rather the result of his financial straits, and was thus not entirely willed. Marianne also acknowledges that she would never have been happy with him anyway; he has proved himself rather lacking in integrity. Elinor shares Willoughby's confession with Mrs. Dashwood as well, who pities the man but cannot fully forgive him for his treatment of Marianne.
Thomas, the Dashwoods' manservant, arrives from town with the news that "Mr. Ferrars" has married Lucy Steele. This news distresses both Elinor and Marianne: Marianne falls into a fit of hysterics, and Elinor appears deeply disappointed. Witnessing her eldest daughter's grief, Mrs. Dashwood wonders whether she ought to have paid closer attention to Elinor's feelings over the past several months.
Not long after, Elinor thinks she sees Colonel Brandon approaching Barton Cottage on horseback, but upon closer look, she realizes that the visitor is actually Edward Ferrars. When he enters the house, and she and Marianne inquire about his recent marriage, he realizes the misunderstanding and assures them that it was Robert who married Lucy Steele. (Now that Robert is the heir to Mrs. Ferrars's money, Lucy has shifted her affections.) Elinor is so overcome by relief that she runs out of the room, unable to contain her tears of joy. Within the next three hours, Edward proposes to Elinor and she accepts, of course, with great happiness. Over dinner that evening, he explains the unfortunate circumstances that first led to his engagement to Lucy. Edward also shares with the Dashwood sisters a note from Lucy in which she informed him of her engagement to Robert and severed all romantic ties with him. When Colonel Brandon arrives at Barton and hears the news of their engagement, he graciously offers to improve the parsonage at Delaford (which he had first offered to Edward when Edward planned to marry Lucy) to accommodate the couple comfortably.
Mrs. Ferrars ultimately reconciles herself to Edward's new situation, though she continues to favor Robert as if he were her eldest son. Elinor and Edward live together at Delaford and frequently invite both Marianne and Colonel Brandon to visit, in the hope that the two will form an attachment with one another. Their plan is successful, for the Colonel and the younger sister become engaged and move in with Elinor and Edward at Delaford. The sisters continue to maintain close ties with their mother and Margaret at Barton Cottage, and the families live happily ever after.
When the servant Thomas first announces the news of "Mr. Ferrars's" marriage to Lucy Steele, Marianne bursts out in hysterics while Elinor maintains her composure in spite of her deep disappointment. Their reactions are ironic on two levels. First, Elinor was the sister with a close attachment to Edward, and thus, she has far more cause to break down in tears. Second, not only do the sisters' reactions seem reversed from what they should be, but the reactions of the men under discussion are reversed as well (though we do not yet know it): it is actually Robert, not Edward, who is engaged to Lucy Steele.
Several critics have objected to the implausibility of the match between Marianne and Colonel Brandon. Brandon is characterized as a clear-headed, dependable, practical man--the total opposite of the romantic and impetuous Marianne. Thus, Marianne's final acceptance of him seems completely out of character, since the marriage requires her to abandon her romantic ideals entirely. Moreover, Marianne and Colonel Brandon barely interact in the novel, especially in the concluding chapters. Thus, it seems unlikely that Marianne would come to love Brandon as she had loved Willoughby; she hardly knows him. Nonetheless, by closing the novel with their marriage, Austen shows the extent of Marianne's transformation: she writes, "She was born to discover the falsehood of her own opinions, and to counteract by her conduct her most favourite maxims." If Marianne's ability to love Brandon is unconvincing, it is because of Austen's great faith in the ability of the individual to remake herself in light of shifting circumstances.
The novel closes with a reminder that the most important attachment in the novel is not that between any man and woman, but between the two sisters. The sisters decide to live side-by-side together with their husbands at Delaford, thereby affirming the mutual respect and affection, which has kept them close throughout the entire novel.
Ultimately, both sisters end up married to the novel's only second sons. Edward Ferrars, although strictly speaking the firstborn, is disinherited by his mother; as John Dashwood remarks, "Robert will now to all intents and purposes be considered as the eldest son." We know that Colonel Brandon is a second son because he has an older brother who married his old sweetheart, Eliza, many years before the novel's plot begins. Whereas these characters are the heroes of the novel, all the eldest sons, including John Dashwood, Robert Ferrars, and Colonel Brandon's older brother, are cast in a negative light. In Austen's day, the eldest sons were the ones who inherited all the family property according to the laws of male primogeniture. However, in spite of these inheritance laws, it is the second sons who ultimately find contentment in the novel; thus, they make happy lives for themselves despite societal and financial constraints.