I'll always argue that Arlington Road is the biggest L ever taken by a main protagonist.
Main character "Michael" is a widower and single father who comes to realize that his new next-door neighbor is a domestic terrorist. As he works to expose his neighbor and stop his plot, his neighbor manages to:
* kill Michael's girlfriend and frame it as an accident
* mock Michael and tell him he killed his girlfriend
* beat the shyt out of Michael and threaten to kill his son
* tricks Michael into driving bombs into FBI headquarters, blowing up both Michael and the headquarters, killing hundreds
* after Michael's death everyone thinks he was the suicide bomber who killed those people
* his son is now an orphan, believes his father was a terrorist, and is still friends with the actual terrorist neighbors
Whole movie you're expecting Michael to get the upper hand and expose those evil people but then
Glad I never saw this movie because I would have been heated for days after watching.