[She's quiet for a few minutes, thinking over what the Master's said and put it against what the Doctor's told her about him. She smiles sadly, relaxing just a bit.]

I 'spose it's silly for me to feel a bit jealous, yeah? I mean, I know he really cares for me, but what you said sounded more passionate.

Why did you let yourself die then? At the end of that year, when he begged you to regenerate, you didn't. Why?