What stories have you invested time in only for them to never be given a proper ending?
This could be in unfinished novels like The First Man by Camus or The Original of Laura by Nabokov.
Or TV shows like Garth Marenghi’s Darkplace (they never did close the gates of hell, but the arbitrariness of the show is part of its appeal). Films left wide open for a sequel that will likely never happen like Jumper.
Or games, like Shenmue where Ryo Hazuki seems doomed to never get revenge on Lan Di for killing his father.
What stories are you still holding a torch for?