He knew it was the right choice.
He knew when he saw the tape, he knew when he found the key, he knew when he found the temple, he knew even before he fused with Connie. He was the reason for everyone's problems. Maybe indirectly through Rose and maybe just because of him but either way it was his fault his friends kept getting hurt. The only way to stop them from getting hurt was to remove himself from the situation. So, yes, he got on the ship. He left the people he loved to make sure they didn't get hurt, but he also left so he wouldn't get hurt either. Living in beach city, acting like everything was normal. It wasn't working anymore. He was scared to to fuse with Connie for fear she would see the things going through his mind that he didn't want to share, or give up. He was there when Blue Diamond and Yellow Diamond cried over their lost friend. He couldn't remember the last time he saw a gem cry that hard over someone else. But living with this much guilt wasn't healthy. It would have been so much easier if he had never been born! Then everyone would have their leader, his dad his mom, and Pearl...her Rose. He wouldn't be a useless gem with human characteristics. He wouldn't be a screw up. He would be alive. And somehow he thought that just might be better. No one seemed to understand how hard it was to be the only one who didn't know his mom. No one seemed to know how hard it was to know that his dad would never be that happy again. No knew how hard it was to watch his friends be taken and almost killed for the gems who wished his mother, and his planet, dead. He felt so alone. He couldn't have human friends in fear of them getting killed, and gems didn't understand how hard it was to be living.
So yeah, it was the right choice to get on the ship. He needed to be responsible for his mom's mistakes. He needed his friends...to be safe. And that meant far, far away from him. Far away from the pain, the memories, the risked all of them. This way he could end all that he caused. He didn't have a future on earth. This way he could go down fighting.
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