Sun Analysis: Spoilers Ahead
The Sun has issue, obviously. But his choice to separate Theia and Proto makes sense in his head, he's saving them an accident. But to them he's practically ruining them. They loved each other more than themselves, and being permanently separated is one of the worst things the Sun could have done.
Now my personal analysis on this is, yes becoming a double planet was risky. But I think one of the big reason Sun didn't want it to happen is because due to the trauma, grief, and loss he has endured. He is scared despite his denial, and it's because of his denial that he can't heal. It's kind of like someone who needs a hug but doesn't know it and refuses to admit it. He can't and hasn't healed, because his denial makes him not take in and process any wake up calls the planets try to tell him. Because he's a dictator, Ganymede was correct about it. He just sees himself as protecting his planets, and he's to focused for wake up calls to work.
