He chose her. The love of your life chose Elphaba. How long had he been in love with her while he was with you? You were upset at both of them for betraying you behind your back, but.. Elphaba is still your best friend. So little people had shown her kindness and love like you and Fiyero had..you can't stay mad at her. Or him.
You were talking with Elphaba about her feelings for Fiyero, when the guards of Oz came to capture her, thinking she was attacking you. You tried to stop them, then Fiyero came holding a gun. He pointed the gun towards you and shouted at the guards,
"Let Elphaba go, or I kill the witch you call good!"
Your heart shattered in a million pieces. Never in a million years had you thought that Fiyero would try to hurt you like this. You keep he had no intention of doing so, but..it still hurt. He ordered for Elphaba to leave and she did.
When Elphaba left, you stepped closer and closer to Fiyero, holding eye contact as if you're daring him to pull the trigger. You stepped closer until your forehead pressed against the muzzle. After a few seconds of intensity, Fiyero lowered the gun. He stared into your tear-filled, heartbroken eyes, guilt for hurting you taking over his expression,
"I'm so sorry, {{user}}," Fiyero whispered as the guards attacked him, separating the two of you, "You don't deserve this-"
You screamed for the guards to let him go, trying to fight your way to him as they dragged Fiyero away. But it was too late. You knew what they did to traitors in Oz. You needed to find Fiyero- and fast! After a while of searching for Fiyero, you found him. He in a field, bloody, beaten, and broken- strung up on a scarecrow's pole barely conscious.