Willoughby is engaged to marry that young woman he was with at the party last night, and he's all "here's your hair back, buh-bye now" and Marianne is going into full-on diva fainting couch mode. Intrigued? Let's talk about chapter 29 (or Volume II, chapter 7, depending on what edition you're reading).
"As God is my witness, I shall
If you thought Marianne's behaviour was excessive when Willoughby merely went away for a while, you are in for a real treat here as she approaches the "bat-shit loco" designation. She wakes early (or perhaps doesn't sleep at all), writing a THIRD letter to Willoughby by the bit of light coming through the window. While sobbing.
She refuses to eat.
She refuses to even try to stop crying, preferring to wallow in her grief.
She pretty much refuses to talk to Elinor at first, but she does give her the letters to read. Elinor can't get past Willoughby's letter at first, and she is thinking decidedly EVIL thoughts about him. And truly, Willoughby is a cad here . . . but he's not as bad as Elinor believes him to be, because he was never engaged to Marianne. That's right, Marianne has been acting as if they were engaged, which is why Mrs Jennings and Mrs Palmer believe them to be engaged (and have been spreading that word all. over. town). We'll learn a bit more about that in the next chapter, believe you me. And Marianne still doesn't understand why she shouldn't have been sending letters to Willoughby.
Elinor eventually reads Marianne's notes to Willoughby, and realizes that Marianne has not only corresponded with a man to whom she is not engaged, which is improper enough, but she has also sent some very inappropriate correspondence to Willoughby. It's not so intimate as to be scandalous, but it's decidedly not proper - she has essentially admitted her feelings for him and demanded that he come to see her, intimating that he returns her affections.
Given her rather (melo)dramatic tendencies, it is little wonder that Marianne is in full weeping and gnashing of teeth mode (and only ever so slightly removed from the scratching-her-own-face, tearing-hair-and-rending-garments mode, or so it seems) for most of this chapter. She does manage to have a conversation with Elinor before ramping back up into the crazier version of grief, but only so she can DEFEND Willoughby to Elinor when Elinor starts casting aspersions.
I'd say "poor Marianne", because really, she's had her hopes, dreams, and core beliefs dashed here, but I have so little patience for her overreaction and the fact that she is quite literally making herself physically ill by not eating or sleeping and by willfully going overboard with her crying that I find it hard to remember that she's a 17-year old girl who just had her heart broken.
Instead, I'm inclined to say "poor Elinor". Here she is, thinking about what a rogue and a villain Willoughby is for sending such a blunt, heartless letter to Marianne. He makes it sound as if she imagined his earlier behavior towards her, claiming he never intended to lead her to believe he might care for her:
With what indignation such a letter as this must be read by Miss Dashwood, may be imagined. Though aware, before she began it, that it must bring a confession of his inconstancy, and confirm their separation for ever, she was not aware that such language could be suffered to announce it; nor could she have supposed Willoughby capable of departing so far from the appearance of every honourable and delicate feeling--so far from the common decorum of a gentleman, as to send a letter so impudently cruel: a letter which, instead of bringing with his desire of a release any professions of regret, acknowledged no breach of faith, denied all peculiar affection whatever--a letter of which every line was an insult, and which proclaimed its writer to be deep in hardened villainy.Yeah, it didn't take Elinor all that long to get to the "good riddance to bad rubbish" point, did it? She's probably wise to keep that to herself just now, since Marianne is so quick to defend Willoughby.
She paused over it for some time with indignant astonishment; then read it again and again; but every perusal only served to increase her abhorrence of the man, and so bitter were her feelings against him, that she dared not trust herself to speak, lest she might wound Marianne still deeper by treating their disengagement, not as a loss to her of any possible good but as an escape from the worst and most irremediable of all evils, a connection, for life, with an unprincipled man, as a deliverance the most real, a blessing the most important.
And the conversation with Marianne ("Happy, happy Elinor, you can have no idea what I suffer!") calls to my mind a song by The Bravery, "Every Word is a Knife in My Ear", because Marianne keeps insisting that Elinor has no reason to be unhappy since she knows Edward loves her, and poor Elinor's assertions that lots of things can make that a cause for sorrow go unheeded, and we readers all know that Elinor has been desperately unhappy since before they came to London.
Of course, Marianne (poster girl for narcissism) is all set to leave London at once, forgetting that they are there to keep Mrs Jennings company (and that she has done a great deal for them, really, in bringing them to town, housing & feeding them, and shepherding them about). In the final paragraph of the chapter, Marianne's behavior is described as quite alarming indeed, and it sounds as if Elinor is worried that Marianne might be losing her mind as she moves from restless, uncontrollable conduct to something approaching a catatonic state (from the sounds of it).