Elinor's reaction when Willoughby coldly breaks up with Marianne via letter and returns all her letters and lock of hair. For all the disagreements they've had and their differences in temperament, the first thing Elinor does when she finds Marianne is to take her hand, kiss her, and just silently hold her while Marianne cries.
Mrs. Jennings and Sir John's reaction when Willoughby's engagement to Miss Grey is revealed. There's never a question about Marianne's reputation—everyone of their acquaintance roundly condemns him for raising her hopes and then callously destroying them in a transparently Gold Digger move. And they even exert themselves not to mention Willoughby when Marianne is around so as to avoid upsetting her (although Elinor is forced to hear their continuous rehashing of the matter).
Marianne's spirited defense of Elinor's artwork when Mrs. Ferrars sneers at it. Even though it attracts more notice than the sneer itself, it just shows how much she loves Elinor. (And Colonel Brandon's regard is increased all the more to see her refuse to sit idly by while Elinor is abused.)
The way Elinor and Marianne come to appreciate and finally love Mrs. Jennings, who may be annoying, a little ditzy, and never shuts up, but who is utterly and unfailingly kind and loyal to them, whatever they're going through.
The originally rude and sarcastic Mr Palmer proves himself to have a heart of gold when the Dashwood sisters go to stay at Cleveland (the Palmer's country estate). He is genuinely concerned when Marianne becomes ill, and wants to stay at Cleveland so that he can help her recover. He also doesn't any annoyance when forced to vacate his house (during Easter, nonetheless), so that Marianne can recover.
Just Elinor and Colonel Brandon's friendship. It's wonderful how a romance novel from the 1800s is able to achieve what is still a point of debate regarding love stories to this day; how can one write a purely platonic but heartfelt friendship between a (presumably straight) female and male character?
Sir John and Mrs. Jennings' complete friendliness and hospitality towards Mrs. Dashwood and her daughters. After how abominably they've been treated by their immediate family it's nice to see someone extending the hand of friendship. And while Sir John and Mrs. Jennings can be a bit much at times, neither of them has a mean-spirited bone in their body.
When Marianne is led out of the ball in evident distress, Mr. Palmer notices and appears rather concerned even though he's caught up in a dance. From then on he goes out of his way to be kind to the Dashwood sisters, offering Elinor any possible assistance when Marianne falls ill.
After her fever has broken, Marianne asks first for Elinor, and then Colonel Brandon.
Toward the end of the movie, when Edward comes calling to the Dashwood ladies. This is after the women had heard that Elinor's rival for Edward's affection - Lucy - had gotten married. During the awkward exchanges, Edward reveals that Lucy had in fact married Edward's younger brother. Elinor's reaction upon hearing that is pure CMoF, but this falls under Heartwarming because of the joyous grin on Elinor's face, and from what Margaret reports spying from her treehouse:
Edward: Elinor. Elinor, I met Lucy when I was very young. Had I an active profession, I should never have felt such an idle and foolish inclination. My behavior at Norland was very wrong, but I convinced myself that you felt only friendship for me, and that it was my heart alone that I was risking. I have come here with no expectations, only to profess, now that I am at liberty to do so, that my heart is, and always will be... yours.
After Colonel Brandon rescues Marianne, who has fallen ill pining for Willoughby in the rain and brings her to the Dashwood home, the following exchange reveals the depth of his feelings for Marianne:
Brandon: What can I do?
Elinor: Colonel, you have done so much already...
Brandon: Give me an occupation, Miss Dashwood, or I shall run mad.
When Fanny Dashwood is commenting on Marianne's prospects after the incident with Willoughby, she remarks that she will be considered "damaged goods". Colonel Brandon knew what her reputation would be... and he still married her. It's true that he could more or less do what he liked, being a man of means with a sizable estate; but Darcy, who had similar (if not greater) wealth and status, felt reluctant to propose to Elizabeth because of the social embarrassment of having the Bennetts as in-laws. Brandon doesn't even seem to consider what society will think.
