When Jess finally gets there (he really did get stuck in traffic) he has a black eye, and refuses to say how it happened. Emily only expresses polite concern, and is otherwise perfectly charming to him.
Rory however, absolutely flips. She is convinced that Jess has got into a fight with Dean, because the two of them talked together at Miss Patty’s. This is very unfair of Rory to make such an assumption, when Jess already told her he wasn’t upset about her talking to Dean – only bothered that he had to find it out from town gossip. But she is so angry with Jess for turning up to Emily’s dinner, late and with a black eye, that she is is no mood to be fair.
The Annotated Gilmore Girls 