Disclaimer: Belongs to the BBC, mmkay? And that person who got arrested for trying to steal the rights wasn't me, O.K? Wasn't me.
Rose knew it looked like she was being selfish, but that wasn't it. It wasn't just about her. It was about him, too. She could still see the pain, the loneliness, the gap where the rest of the Time Lords should have been.
Never mind her pain, what about the Doctor's? He did it alone. All the time. And she'd wanted to change that so badly. So very badly.
He'd changed her, she knew that. And she thought that she'd changed him. Helped take some of that pain away. They were good for each other. They made each other better.
And now she was expected to say "Yes, I'll leave you and go live in a parallel world where I'll never see you again ever."
Rose was not going to leave something like this behind. It would take the force of something stronger than mere Daleks and Cybermen to do that. And Rose was terrified she really was, but she didn't have time to cower in fear, she only had time to fight.
You could scream all you liked, if you stand around doing nothing the bad guys win.
And it hurt the most when she had to fight the Doctor. He wanted her to go. He wanted her to be safe.
She was stubborn and she remembered how she felt when it had happened before, before she became the Bad Wolf. Sometimes she got flashes of that time when she'd been possessed, Daleks turning to dust at her fingertips.
So she teleported herself back and refused to budge and in the end she knew the Doctor would let her stay because he didn't want to lose her either.
Rose was sure they'd get through this and out the other end together.
That's why it hurt so much when it went so terribly wrong.