While in Herbology, Harry tells Ron and Hermione about the memory he witnessed in Dumbledore's office in the previous chapter. As class goes on, their discussions range to Slughorn's parties, in which Ron is jealous of Hermione and Harry because there is a Christmas party coming up, and Slughorn is making sure Hermione checks with Harry first so that he can't squirm his way out of it. This causes Ron to make rude remarks about Hermione hooking up with [=McLaggen=] until Hermione informs him that they are allowed guests, and she was planning on bringing him. This causes Ron to turn rather sheepish, and for Harry to think about the expectancy of something going on between his two bestfriends, which he didn't find very surprising.
As the first Gryffindor Quidditch match approaches, Ron is getting extra nervous, bringing back the insecurities and lackluster performances he had the previous year, to the point where he accidentally punches one of Ginny's friends during Quidditch practice to insure she doesn't make a goal. Trying to comfort his bestfriend after a practice, the two come across Ginny and Dean in an abandoned hallway, making out. Ron scolds her, [[FieryRedHead but Ginny won't let him yell without her yelling back]], leaving Ron in a nasty mood, and Harry to deal with the confusion of his affections toward Ginny, previously thinking that their relationship was as a brother and sister, but starting to sense the possibility that there was something more. On the way back to the common room, Ron asks Harry about whether or not he thinks Hermione and Krum ever kissed. Harry knew that the best answer would be to remain silent, but Ron reads his expression.
Unfortunately, Ron's sour attitude does not die down, and makes him even worse at Quidditch until, finally, the day of the match arrives. However, at breakfast Hermione believes she saw Harry slip something into Ron's drink. Believing it to be Felix Felicis, she tries to persuade Ron not to drink it and scolds Harry for doing it in the first place, until Ron just decides to ignore her and finish his breakfast. On the way down to the Quidditch pitch, Ginny informs them that two Slytherin players, including Malfoy, are unable to play, leaving Ron with the conclusion that their conditions today were very lucky. It is then when Ron puts two and two together and has an epiphany. Harry, however, disregards this makes his way down to the field as usual.
Thinking that luck is on his side, Ron plays one of the greatest games of his life, and Gryffindor wins the game. However, Harry tells both him and Hermione in the changing rooms that he did not put any Felix Felicis, and shows them the tiny flask of it, full and unopened. Hermione is shocked by the news, which Ron takes as a personal insult, stating that he can save goals without help, leaving Hermione in tears, sick of Ron's attitude towards her all week. Harry makes his way up to the castle after Ron and Hermione have both left, to find that the common room is celebrating after Ron's victory. To Harry's surprise, Ron is having his own personal celebrations in the corner of the common room with Lavender Brown (as Ginny puts it, they look like they're trying to swallow each other's faces). Thinking he saw a mane of bushy hair just sweep around a nearby corner, Harry goes to comfort a heartbroken Hermione, who can no longer stand to be in the same room as Ron.