I was on the Dean and Rory train, just like everyone else, until I recently re-watched the show and noticed that Dean was actually a terrible boyfriend to Rory a lot of the time. He had the sweet and innocent facade, but there were numerous times when he was actually a really emotionally abusive boyfriend to Rory.
I'm not saying that Rory's other two boyfriends were complete gems, but while Logan and Jess grew and matured over the seasons, Dean continued to be controlling and abusive mentally to everyone around him. The worst part about this is that everyone, including Lorelai, saw him as "the nice guy" and not for what he really was.
It started with small things, like how talked about wanting a "Donna Reed" style housewife, or how he made Rory feel bad about liking school dances, but it progressed into outright abuse later in the series. For example, Dean tells Rory that he loves her and then waits no more than thirty seconds before blowing his lid, yelling at Rory for not saying it back. Rory ends up begging for Dean not to be mad at her, which is a trend that's repeated throughout the majority of their relationship.
Some of Dean's worst traits came out in regards to Rory having guy friends. Let's start with Tristin. Rory and Tristin were hardly friends for the majority of his presence in the show, but Dean consistently fed into the drama caused by Tristin and even said "I would kill you" at the Chilton dance when Tristin tries to start a fight. Red flag, much? After this, he continues to blame Rory for Tristin's immature behavior and makes it out to be her fault that he acts the way. Typical abuser trait.
Dean's abusive nature is heightened even more when Jess comes to town. Yes, I know that Rory liked Jess, but Dean still had no right to flip his handle the way he did (before he even knew that Rory had feelings for Jess). Going beyond calling Rory's house about thirty times in one day. he also got mad at her every time she even talked to Jess - even when it wasn't her fault. He was extremely jealous and clingy, and even tried to pick a fight with Jess multiple times. Of course, all this pushed Rory away, which made Dean even more possessive. Vicious cycle.
Finally, Dean breaks up with Rory in public - twice. In one of those times, he even yelled at her in front over everyone.Then, he goes and marries someone (at eighteen years-old) while he's still in love with Rory. While in this marriage, we not only see just how emotionally abusive and immature he is towards Lindsay, but he has absolutely no hesitation when he gets the chance to cheat on her with Rory. He sweet talks his way back into Rory's heart and pounces just when he knows that he can. Later in that episode we also see him go home and yell at his wife for answering his phone while he was out. She sheepishly apologizes, which may be a hint at their abusive relationship, but regardless, it's difficult to watch the whole thing happen. Dean is obviously taking out his guilt on Lindsay, who has been nothing but the perfect housewife Dean has always wanted.
Thankfully, Dean's presence in Rory's life ends not long after they sleep together, because I couldn't bear to see him emotionally abuse Rory or anyone else in the show much longer. Thankfully, we see in the Gilmore Girls revival that Dean has indeed matured and is finally happy with his life. Took long enough.