Old comment, but I just watched the movie. I feel that Caleb actually did just leave. He slipped the first time and without hesitation John pulls him back up. Then Caleb stays at the edge and doesn't move to a safer distance, which I would think people would do after almost falling. The second time John again, without hesitation, secures a grip and keeps him up. Caleb has that smirk on his face while John's face shows a look of concern. I took it as Caleb sort of testing John. It's clear that John doesn't like him but yet he still saves him twice. I think Caleb got what he wanted, Ann, and saw no need to do anything else. I think him folding his hands at the end was him not taking Ann for granted any more.m