Amy was hurt by the Doctor's distant attitude towards her, but she understood. He had no idea who she was, and meeting someone from your future could be dangerous. She was reminded of the way her Doctor acted around River at the Byzantium.
When Galen mentioned her Doctor, it was more than she can take. "I think I'll take you up on that cabin," she said quickly, and hurried off without waiting for him to show her where it was. As soon as she'd rounded a corner and was out of sight of the cargo bay, her knees gave out and she slumped against the wall, sliding down to the floor. The tears flowed from her eyes before she could stop them. She hadn't seen her Doctor in weeks. Not since that day in the library when the Angel had brought him to her. He'd gone off to do... research on how to get them out of here, told her not to worry, then vanished. He left her behind, again. Seeing Donna with this Doctor, and the way he obviously cared about her was just too much.