He watched her turn to stone. Right in front of his eyes.
He told Donna not to blink at the weeping angel they had just came across on the abandoned ship . And she hadn't, but the angel still grabbed her by the wrist, the Doctor thought she was going to be zapped back in the past. He had no idea why this angel moved, when she didn't blink at all.
He stood there, staring at his best friend, his hearts breaking ,trying to figure out why this weeping angel was acting strangely. He then grinned , trying to make light of the situation.
' Oh well Donna Noble, at least you can't call me Spaceman anymore'