Unpopular Opinion:Dean was not a jerk for breaking up with Rory on the dance floor.
Growing up, I always thought Dean was a jerk for breaking up with Rory at the dance floor in front of everyone. But now on my million-th rewatch, I feel it was completely understandable of him to break up with her. Rory had an emotional involvement with Jess, they did even kiss(though Dean didn't know that). It had been going on for so long. He was feeling jealous and then he was cooking it off and then he was adjusting to the calm in their relationship because Rory was at odds with Jess so their relationship was good again. And then she provokes Jess at the Dance off. I agree it was in retaliation to him provoking her but he was mature when he didn't get involved in their altercation. But then at the dance floor she was dancing with him but staring at Jess. That gotta sting.
It was the straw on the camel's back. All those months maybe year of seeing Rory pull away while telling him,"No!I love you." Well that's gotta come out sometime.
I agree the mature thing would have been to break up with her afterwards. Or the mature thing would have been to break up with her when she was first getting involved with Jess and started ignoring Dean. But hey, they are what 16, 17 year olds? We are expecting way too much maturity from them if we are.
Edit: I just reached the scene in the episode where Dean actually breaks up with Rory and oh my god it is so much worse. She is dancing with him but ranting about Jess or fighting with him while completely ignoring Dean. I don't think Dean was in the wrong at all. And I don't think he should have taken her aside and broken up with her. God this girl ! And afterwards, she isn't even affected, she is like oh well yeah it is all true. So now what Jess. NOW WHAT JESS? Oh my god! So all this time you were just waiting for Dean to take himself out. What a wuss. Ugh!