The next morning, Marianne is up pre-dawn, writing a desperate letter and sobbing. Elinor tries gently to ask her what's going on, but she says nothing, claiming that her sister will find everything out soon enough.
At breakfast, Elinor tries to distract their hostess – the last thing she wants is for Mrs. Jennings to start nagging Marianne.
A letter arrives (clearly from Willoughby). Mrs. Jennings benignly says that Marianne must be very, very much in love, and asks Elinor when her sister is to be married. Elinor deflects this by saying that news of Marianne's engagement were just a joke.
Mrs. Jennings will have none of this, and says that everyone knows about Marianne and Willoughby. Elinor warns her that she'll feel bad for spreading this rumor soon enough.
Elinor flees the breakfast table to check on Marianne.
The two sisters weep together for a while, and Marianne hands over Willoughby's letter to her sister.
The letter is cold-hearted and brief. Basically, it just says that Marianne is crazy for thinking that Willoughby ever cared for her, and that he's in love with someone else. He's also returned all of Marianne's earlier letters.
Elinor is shocked, disgusted at Willoughby, and uncertain of what to do. She excuses herself from Mrs. Jennings for the day, saying that Marianne is unwell, then goes back to tend to her sister.
Marianne is so miserable she wants to die. Elinor begs her to be more reasonable, and Marianne says that she wishes she were as happy as Elinor, who she supposes to be content and beloved by Edward.
Elinor holds her tongue, beyond saying that things aren't as perfect as Marianne makes them out to be. She rather feebly makes the excuse that she can't be happy when her sister is so miserable.
Elinor tries to make Marianne see the bright side – after all, what would have happened if she hadn't discovered that Willoughby was such a bad dude, and they'd continued their engagement?
Marianne reveals something truly shocking – they were never engaged in the first place.
Apparently, Willoughby didn't ever actually come out and say that he loved Marianne – she just assumed it from his treatment of her.
Elinor, trying to get to the bottom of this, turns to Marianne's returned letters to Willoughby.
They show increasing desperation, asking Willoughby why he won't visit, and demanding that he explain his coldness. She can't believe that he didn't answer such heartfelt letters, but at the same time, she can't believe her ridiculous sister wrote them in the first place.
Marianne reiterates the fact that she's certain that Willoughby loved her, even if he never declared it. She blames the world, not Willoughby, for this horrible development – she's sure that someone else changed his mind, and that he himself could never be so awful.
After rereading the letter, Marianne quickly changes her tune and blames Willoughby all over again. She wonders who this vixen is who's stolen Willoughby's affections.
Marianne, in a fit of agitation, demands that they go home the next day. Elinor forcefully puts her sister back to bed, making her relax there.