Gainax Ending
When an anime makes you fall in love with a character, then smacks you in the face with a plot twist so hard you forget your own name.
I was on cloud nine, then my favorite character was killed off in the last episode. My heart shattered.
It was like getting a gold medal, then getting kicked out of the Olympics.
I watched the whole thing, and then my character just vanished. No explanation. No closure. Just a giant middle finger.