River wasn't completely stupid. She knew that he was about as trustworthy as a bag of cats. And to be fair, so was she. They weren't going to trust each other. But if helping him made more of a mess for the Doctor, then she was all for it. Anything to make him yell and pace around and squirm. She liked driving him a little mad. She was going to be true to her word though, she thought she could help him with his problem.
Of course she needed to see his problem first hand. So she made up a meal that was sure to sustain him for quite a while and then went to the library so that she could give it to him. Then they could see about fixing him. She wandered in, hearing his voice and her hands full of a tray. On that tray was all the food.