This is the bad ending of "The Return of Harmony" where Discord never defeated and Twilight become discorded permanently.

Edited vector:https://derpibooru.org/images/2713947?q=discorded+twilight%2C+crying

Background used:https://www.deviantart.com/liamwhite1/art/Discorded-Land-426739404

Story:
When Mane 6 uses elements to turn Discord back to stone, The elements seem to be stopped. Although Discord has won against Mane 6. However, Twilight was told by discord:"Twilight, You are defeated. I win. But I didn't turn your friends to become opposite."
The Mane 6 gasped. Twilight's colors begin to turn grey. And then, Twilight has turned grey. And telling mane 5 to abandon her. "You're… not my friends either… Abandon me, and all hope. Because I failed equestia…" Twilight said. The Mane 5 was right. He decided to abandon twilight and leave her alone. But he give his elements to twilight. Twilight was alone in the discorded landscape, begin to cry. Twilight broke his elements and crown then he said:"Friendship Isn't magic… The elements became useless… My friends abandoned me… If Discord Win…. I turned grey…." Twilight is now crying. Although mane 5 was not discorded, Twilight is the only one who become discorded If she was defeated.