One of the most popular supporting characters during Gilmore Girls' early seasons was Dave Rygalski (Adam Brody), the boyfriend and bandmate of Lane Kim, but what happened to him and why did he never return? Gilmore Girls' main setting, the town of Stars Hollow, was filled with weird and wonderful characters. Dave Rygalski first appeared in season 3's "Application Anxiety", where he is seeking a new drummer for his band. Lane expresses her interest, and the two immediately hit it off and, eventually, start dating.
Of course, because of Lane's mother, Mrs. Kim, being incredibly strict about all aspects of her daughter's life, Dave and Lane's burgeoning relationship is kept secret for a while. Eventually he starts to gain Mrs. Kim's trust, largely by pretending to be a Christian guitarist. Lane and Dave were one of Gilmore Girls' strongest romantic couples - and were certainly among its most popular with fans - but unfortunately the relationship wasn't given the chance to fully run its course.
By the end of Gilmore Girls season 3, the teenage characters on the show were heading off to college. For Rory, that meant Yale over Harvard. Lane, meanwhile, went to a Seventh-day Adventist College at the request of Mrs. Kim (although she didn't last long), but Dave didn't stick around Stars Hollow, or anywhere close. Instead, Dave went off to college in California, and was never seen again on Gilmore Girls. He was mentioned a few times, but it wasn't long before he and Lane broke up, following an argument and the fact that a long-distance relationship wasn't working for them. Of course, the real reason for this is logistically it didn't make sense to keep Lane in a relationship with someone who wasn't appearing on the show, and Dave wasn't going to return because Adam Brody was by then busy on The O.C. That series is why Dave left in the first place, and why he didn't return even for a guest spot.
Given there's no further mention of Dave Rygalski in Gilmore Girls after the breakup - and he doesn't return for the Netflix revival Gilmore Girls: A Year in the Life - then it's safe to assume that he stayed out in California and never returned to Stars Hollow. If he did, it seems unlikely that he met up with Lane: not only was he replaced in the band, but she also started a relationship with another of their bandmates, Zach, to whom she'd later fall pregnant.
Of course, Gilmore Girls ultimately failed Lane Kim through this storyline, allowing Zach to go off and tour as a rock star while she was stuck at home, which is something that presumably wouldn't have happened had Dave not left. Amy Sherman-Palladino had wanted Brody placed under a contract so they could keep him around longer, but it never happened and he ended up taking the job on The O.C. Things would've no doubt been very different (and better) for Lane had Dave not left for California.