He can't help it. Because he knew something about the cause of his parents divorce, he feels as if he should have been able to make things right. One side of him knows that, as a child, he really couldn't fix things, but that doesn't make him stop thinking about it. It is also a diversion--most of his mental energy has to be on surviving, but when he does have some time to think, that is what is going to pop into his head. After all, if his parents hadn't divorced, he wouldn't be stranded because he never would have been on the plane.