Daniel thinks that when a person is born, God or aliens should give them free passes to do things over or take things back. He wishes he could change what he said. He knows that Natasha will understand, but Daniel thinks he can't do it. He asks to try the moment again, and Natasha smiles a huge smile that makes Daniel feel as though everything will be worth it.
Natasha's extremely positive reaction to Daniel's decision shows that emotion and reason are absolutely not at odds. Further, it suggests that marrying the two can bring about positive emotions for even the most rational people.