The viewer is quickly made aware that although Rory hasn’t felt able to write to Jess over the summer, she is hoping to see him at the End of Summer Madness Festival. It is three hours before Dean is due home, and she is apparently planning to make the most of them. She insists on going to the festival in town, even though she’s only just got home from the airport, and changes into a nice dress. Lorelai insists on calling this “changing for Dean”. The Dean who isn’t there.
However, her plans are scuppered when she finally catches a glimpse of Jess – and it turns out that instead of spending the summer pining over her, he’s got a girlfriend (a blonde one, so you just know she’s stupid and awful!). Did he hope that Rory would see them and get the message that Jess Mariano is not some sap you can toy with, then toss aside while you waltz off to Washington for the summer? If so, message received.
Jess is kissing his girlfriend up against a tree, in flagrant view of the whole town. It’s very similar to the way Dean and Rory used to kiss against trees and shelves in the market, which must have been difficult for Jess to witness, so he seems to be getting his own back. Rory is getting a tiny taste of what Jess has been through for the past few months.
Rory and Lorelai almost immediately get into a fight at the festival when Lorelai says it’s lucky she didn’t throw “everything” (ie Dean, he’s everything now) away for Jess. She brushes Rory’s feelings for Jess away as a “little crush”, until Rory tells her mother that she kissed Jess at Sookie’s wedding while there with Dean. Lorelai is indignant on Dean’s behalf, conveniently forgetting that she herself slept with a pregnant woman’s boyfriend at the wedding, and doesn’t really have much high moral ground to stand on.
It is set up in the story, and repeated several times, that Rory went away for the summer, and therefore has had no contact with Jess since the wedding. The trouble is, the wedding wasn’t at the start of summer vacation, Rory still had two or three more weeks of school left. And she didn’t go to Washington for the summer vacation, only for the last six weeks of it. That makes at least eight weeks that she and Jess were in Stars Hollow together and somehow managed not to talk to or even see each other.
It doesn’t seem plausible – Stars Hollow is a small place. Presumably Rory was avoiding Luke’s diner in support of Lorelai, and busy with school, and getting prepared for Washington, but I can’t see how she avoided Jess for six weeks straight unless he was also determinedly avoiding her. If so, suggesting that he was very hurt and confused about being unexpectedly kissed, told to keep quiet about it, and then seeing that Rory and Dean were still together as if nothing had happened.