Touch and go

Hi,
I can't understand what 'touch and go' means in the context:

Gabrielle finally confesses her fears that Carlos won't find her as beautiful as before and he tells her when he first knew he wanted to marry her. It was when she ate ribs and was laughing happily, not caring that she'd made a huge mess. "It had nothing to do with your looks," he assures her. "Do you know when I decided I want to be with you forever? About two seconds ago," she says. "Up until then, it was pretty touch and go."

Thanks a lot.