She smiled, looking a bit distracted, though. "I worry about my Donna.." she confessed. They'd talked about it once before, when Jenny had worried that Donna was compromised. She was always pushing people away. Most of the time when Jenny pushed back, Donna conceded and let her come along, but now Jenny was starting to falter. Donna was supposed to take care of Jenny. She couldn't be the one responsible for making sure Donna stayed alive. She worried about all this pushing.
Part of her wondered if it was a good idea for Donna to even have her own TARDIS. Sure, she could get into plenty of trouble without one, but was it such a good idea for her to have that sort of power when she was so self-destructive?