Why did Ron and Hermione fight after the Yule Ball?

From what I've gathered in the book Ron is upset for a few reasons.

1. First and most importantly Ron is starting to realize that he has feelings for Hermione, particularly as he saw how beautiful she was in her dress with her hair down.
2. He's jealous of Viktor Krum for two reasons:
   • He is a huge fan of Krum himself and would love to spend a day talking to him.
   • He's unhappy about Krum, not him, being with Hermione.
3. He is slightly upset about the fact that Hermione didn't tell them, and (after thinking about it) that she's with the enemy.
4. He also just had an awful night, first with his ugly dress clothes, and then with a bad date.

All this resulted in his outburst to Hermione, and her reply definitely showed that she was interested in Ron and that she felt he was stupid for not seeing it. Her outburst shut him up because he realized how stupid he was being.

Yes, Ron is jealous. He's masking his jealousy by claiming that he doesn't want Hermione to go out with the enemy (Krum) when the truth is that he's jealous that Krum is taking out Hermione and not him. Hermione realizes this “Next time there’s a ball, ask me before someone else does, and not as a last resort!”

I think you guys are missing the larger point. Hermione was mad because Ron basically acted like she had no feelings. Ron really didn't have feelings for her at that point. He just wanted a date, and Hermione would fit the bill. He didn't think that anyone else might really want to ask her out, and he didn't think that she might want to go out with anyone else. He figured she would just wait around, and be grateful when he deigned to ask her as a friend. And then she showed that she had a mind of her own, and Ron's response was "How could you!"

First, Ron is going through a lot of emotions, the most powerful one being jealousy. As anyone could see that read the book, Ron felt this jealousy for a lot of the book. First with Harry getting into the tournament(Harry was getting attention that Ron never got and wanted as his mother was nice to him, but he was ignored by people at his school and his mother never pampered him like she did Harry) and then with Victor Krum basically stealing the girl he liked (or didn't know he liked till then).

The Yule Ball argument was a progression that came on slowly and simmered until it burst on that night:

Another note is that he is also learning of his feeling of for Hermione, but like all the books he doesn't know how to go about them.

Ron wanted to go to the ball someone (Hermione being one candidate), but he waited till a short time or so before the Yule Ball to even approach the idea of taking her. And then when she turned him down, he thought this as another slight, not that someone else would have wanted to take her as well. He thinks that she will be waiting for him, but is not and that irks him.

From pg.400 Chapter 22 "The unexpected Task"

"......But Ron was staring at Hermione as though suddenly seeing her in a whole new light.

"Hermione, Neville's right- you are a girl......."

"Oh well spotted" she replied acidly.

"Well- you can come with one of us!"

"No, I can't," snapped Hermione.

"Oh come on," he said impatiently, "we need partners, we're going to look really stupid if we haven't got any, everyone else has............."

"I can't come with you," said Hermione, now blushing, "because I'm already going with someone."

"No you're not!" said Ron. "You just said that to get rid of Neville!"

"Oh did I?" said Hermione, and her eyes flashing dangerously" Just because it's taken you three years to notice, Ron doesn't mean no one else has spotted I am girl!"

Then slightly later after she leaves.

"She's lying," said Ron flatly, watching her go.

"She's not," said Ginny quietly.

"Who is it then?" said Ron sharply.

I'm not telling you its her business," said Ginny.

"Right," said Ron, who looked extremely put out....................."

From pg. 399 Chapter 22 of Goblet of Fire "The Unexpected Task", Ron said this:

"......................but she told him she was already going with someone. Ha! As if! She didn't want to with Neville...... I mean who would?"

From that quote you could see that he was feeling superior and felt that she would always be there, because she wouldn't get with the dregs(in his opinion or anyone higher up wouldn't want her, he probably still sees her as the bookish nerd with the bushy hair and buck teeth). We know from this same book and chapter that he has a certain "idea" of what beauty is. He probably doesn't understand his feelings for her yet either, as he is either 14 or 15, possibly 13(very young and going through puberty).

And on pg.394 Ron talks more about his choices in partners which insults woman and offends Hermione.

Once he realized who she went with he probably felt a even more slight and as she went with Victor Krum(Quiditch player and Champion for his school), but she didn't go with him. He was probably feeling inadequate.

Chapter 23 The Yule Ball

"Ron was watching Hermione pass with narrowed eyes....."

Then on Chapter 23 The Yule Ball pg. 420-421

Ron has a beginning argument with Hermione and explains his displeasure as due to the fact that Victor is from Durmstrang and that she is supposed to be helping Harry. But he himself had no problem with ignoring Harry and treating him poorly for the first challenge, so that is probably not it. Also, he destroys his Victor Krum merchandise after that argument, when he of the 3 friends was before the biggest supporter of Victor Krum.

And then that brings me back to your quote.

Hermione and Harry knew that his anger was at least jealousy or a blooming love whichever. That is why he

"................mouthed soundlessly like a goldfish out of water.........................." and he "..............sputtered, looking thunderstruck, "well- that just proves- completely missed the point-". Chapter 23 The Yule Ball, pg. 432.

From that quote he is probably realizing what they are saying is true and is embarrassed.

But Harry and Hermione both knew that Ron liked Hermione and the fact that he only realized it till then, probably because he was too busy looking at Veela and playing. He vented his anger as not liking the fact she was fraternizing with enemy, but it was really jealousy.

Also, other people went out with others from other schools, but he only chose to zero in on Hermione. Because it was personal.

Another thought is that he thought Krum was just using her to get answers, like he does during school. Maybe he was telling the truth during the ball and he was just trying to look after her best interests.

The way I understand the situation is that Ron is angry at Hermione's hypocrisy.

Hermione never showed interest in, and sometimes showed dislike to, Quidditch, and even showed dislike towards Krum. She complained about Krum's presence in the library; that gives everyone including Ron the idea that Hermione dislikes Krum. Ron on the other hand loves Krum and dislikes Hermione's complaining about him.

Then he sees Hermione with Krum at the Yule Ball, and that's enough for him to get angry at her. He's not really angry at Krum, he's just upset that he chose to go out with a person Ron likes to go to the Yule ball or have an unknown secret liking for - and that person means Hermione, not even liking Krum before.

So in summary: Ron likes Krum and Hermione, Hermione dislikes Krum, Hermione goes out with Krum, and that makes Ron angry.

I think it's more like Ron doesn't know what to do with his feelings for Hermione that he hasn't quite figured out yet, and when she gets upset with him for being upset with her, he tries to play it off because he doesn't want to admit that she might be right.

I don't think Hermione disliked Krum as a person at all, I think what she found unattractive was his impact on those around him (the group of girls following him around all the time), and once she was able to separate Krum from his celebrity status, she really did find him to be quite likable. Getting back to the point, though, Ron was probably already upset for lots of reasons (the Yule Ball just wasn't a good time for him) and his unsorted feelings combined with seeing Hermione enjoying herself with someone he admired but at the same time someone he was unconsciously competing with just tipped him over the edge and he snapped at her.

Basically, Ron is starting to see he likes Hermione. So, he is jealous of the fact that she went with someone else. Also, Krum is basically his idol so he is feeling very insecure. He feels that Hermione wouldn't like him.