Elizabeth insisting on walking the three miles to Netherfield to take care of Jane. She has no time for the petty games that Bingley's sisters try to play and soon finds that the only tolerable person there is Mr. Bingley (Darcy still being in jerk mode at this point), but she puts up with it because she only cares about helping her sister get better.
Elizabeth and Jane's relationship in general. They love and respect each other so much and are always ready to look out for one another: absolutely ideal sisters.
All of the times when Darcy cuts down Caroline for belittling Elizabeth.
Georgiana Darcy's eagerness to meet Elizabeth, because her brother has been talking of Elizabeth in such glowing terms.
Bingley proposes to Jane at last; Jane gushes to Lizzy that she doesn't know how one person could possible contain so much happiness.
Every damn thing Darcy does as soon as he discovers Elizabeth in distress after reading Jane's letter in Lambton. He immediately forgets whatever it was he had been about to say and focuses himself entirely on helping her as best he can, even though at this point he still believes he has no chance to win her heart. If any proof was ever needed that Darcy truly loves Elizabeth, this is it.
Further proof: not only does he not tell her of his help, he insists that no one else tell her either, specifically because he doesn't want her to feel any obligation to him. He's really and truly not doing it for any reason other than that he loves her and wants to make her happy.
All of Darcy's interactions with Georgiana. He's considerate of her shyness, but also encourages her gently to be more social and speak to Elizabeth herself. Every scene they share makes it clear how much they love and care for each other.
Darcy ready to spring to Georgiana's aid when Caroline obliviously drops Wickham's name in yet another dig at Lizzie. Lizzie herself tactfully intervenes to help her shy new friend; she and Darcy share a look of sympathetic understanding.
The scene at the end of the 1995 miniseries where Elizabeth explains to her father why she's marrying Mr. Darcy. When she's finished, he says "If that's the case, then he deserves you. And I could not have parted with you for anyone else." He then kisses her while blinking back tears.
Also in the BBC version, when Darcy is dealing with Wickham in the flashback (following the latter's attempted seduction of Georgiana) we see Georgiana waiting anxiously outside the room, then Wickham departs and Darcy sternly orders her in...and tenderly embraces her.
A subtle one from the first meeting between Elizabeth and Darcy; when she says that poetry is a terrible way to court someone, Darcy immediately asks what she would suggest instead. Underneath that cold, brusque exterior, he's actually completely unsure what to say or do and trying to calculate how he can court her.
There's something oddly adorable about Darcy giving his sister that "Shut up!" look every older sibling has given their younger sibling at least once. Haughty and sarcastic as he can be, he still acts like any other big brother who was just embarrassed in front of his crush.
Darcy helping Bingley rehearse for his apology and proposal to Jane. The scene takes place at a distance, so the audience can only catch snippets- but it's clear that Bingley is frantic, constantly pacing and fluffing whatever he planned to say, and Darcy is almost hilariously uncomfortable- but sticking with it nevertheless for the sake of helping his friend.
Toward the end when Darcy and Elizabeth meet again:
Mr. Darcy: You must know... surely, you must know it was all for you. You are too generous to trifle with me. I believe you spoke with my aunt last night, and it has taught me to hope as I'd scarcely allowed myself before. If your feelings are still what they were last April, tell me so at once. My affections and wishes have not changed, but one word from you will silence me forever. If, however, your feelings have changed, I will have to tell you: you have bewitched me, body and soul, and I love, I love, I love you. I never wish to be parted from you from this day on.