Something told her to get off the plane and come after him. At the time she thought that something was the need to get one last kiss. But now it looked a lot like it was some unexplained intuition that was telling her he was in deep shit.
Knowing she was a poor liar under pressure kept him from telling her the truth. He remembered far too many occasions as kids when they had formulated a story to stay out of trouble with their parents and she had blown it within seconds.