"I've been trying to learn. I need to get back to where, to when I belong. I need to get you back, and the more time I spend around you the more likely I'll let something loose that you aren't supposed to know."

Like you piloting a Dalek saucer to your death by nuclear detonation.

"I don't mean to be avoiding you, Lucie, but right now, it's better. Because you are my friend. And I'd rather not see you harmed by something you aren't supposed to know."