"She had seen enough of [Lucy's] pride, her meanness, and her determined prejudice against herself..."
From chapter 8:
"A woman of seven-and-twenty," said Marianne, after pausing a moment, "can never hope to feel or inspire affection again...
Strangled by the Red String: The novel never really explains why Edward and Elinor fell in love, focusing much more on Marianne's romantic relationships. Emma Thompson went out of her way to rectify this in the film, to the point where many fans consider the film superior, at least in this regard; the 2008 miniseries takes its cue from Thompson's screenplay, and is much the better for it.
Edward's persisting in the engagement is portrayed as the honorable thing to do. However, the modern reader can't help noticing that Edward's stance would lead him to a life-bonding contract with an individual he no longer cared about. The engagement is also technically void (made by two minors without their parents' consent), meaning it's not legally binding; Edward sticks to it because he feels morally bound. As one fanfiction writer puts it, "I made a promise when I was a teenager, and it is only honourable that I be bound by this promise for all eternity." With that said, Edward's breaking off the engagement after its reveal would have absolutely ruined Lucy's reputation and destroyed her chance of ever marrying, let alone marrying well. Given her financial situation, that would be a sentence to ruin. Only women in the Regency era could break off an engagement, and even then it was a risk; Lucy only got away with it because she married Robert immediately thereafter.
Sixteen-and-a-half Marianne's objection to Colonel Brandon on the basis of his age (she herself says he's old enough to be her father) would not be considered a sign of her immaturity today. (Getting married as a teenager itself goes without saying.) Mrs. Jennings points to his age as a major point in his favor, since young men are more likely to shift in character as they establish their position in the world.
On the flip side, thirty-something Colonel Brandon's age would not be considered a sign in his favor for sixteen-year-old Marianne's hand today. In fact, Colonel Brandon being attracted to a teenage girl because she resembles his teenage ward, who resembles her mother, who was the sweetheart of his youth, and who could have been his wife had she not been forced to marry another, would be considered more Squicky today and less sentimental and romantic. The 1995 film ages Marianne up accordingly.
Continuing in the age dissonance, Willoughby's is thoroughly castigated for the crime of impregnating and then abandoning young Eliza, but not for the fact that she was fifteen at the time.
Wangst: Deliberate — Marianne's response to her romantic woes begins to take on this edge, which to her credit she eventually comes to realize.
Watch Imelda Staunton (Mrs. Palmer) interact with Emma Thompson in this film, then follow it by watching their characters interact in Harry Potter and the Order of the Phoenix. You might never look at Dolores Umbridge and Sybil Trelawney the same.
Hugh Grant and Emma Thompson play siblings in Love Actually. Emma Thompson is also married to Alan Rickman in the same movie.
Hugh Laurie playing sarcastic Mr. Palmer years before House. And stealing the show.
Values Dissonance: In the movie, Colonel Brandon was forbidden from marrying his cousin Elizabeth because she had no money. In the book, she was forced to marry his brother specifically because she did have money - and it had to stay with the oldest son to keep it in the family.