Lots of spoilers.
Brazil, https://en.m.wikipedia.org/wiki/Brazil_(1985_film)
You are lobotomized and you are happy. Kinda the dream really, I would get one tomorrow if I could be assured of the outcome.
Delicatessen https://en.m.wikipedia.org/wiki/Delicatessen_(1991_film)
You kill the person trying to kill you for meat. Maybe that's happy
Betty Blue
https://en.m.wikipedia.org/wiki/Betty_Blue
You smother with a pillow the only person who understands you after she loses her mind
12 Monkeys https://en.m.wikipedia.org/wiki/12_Monkeys
We are all insane, but least insane wins (loses horribly).
I could go on but you see what my life is like.
narrator- he did go on
Bonus: Apocalyplse Now https://en.m.wikipedia.org/wiki/Apocalypse_Now
You go insane and try to do the right thing to find redemption, to achieve this you kill people
Inception
https://en.m.wikipedia.org/wiki/Inception
You have no idea if you have lost the plot (are living in reality) or not, at the end you don't care.
Older.
Un Chien Andalou.
https://en.m.wikipedia.org/wiki/Un_Chien_Andalou
BuΓ±uel and Dali team up, you rape a young woman, you end up buried in sand on the beach.
The Quiet Earth. https://en.m.wikipedia.org/wiki/The_Quiet_Earth_(film)
You think you are the last man on earth, then you find a chick, you bang her, then she finds a more virulent dude. You let them both die.
ETA: added context. 2nd edit formatting