Life of Pi is filled with sad occurrences that the protagonist, Pi Patel, has to deal with and learn to survive. The first is the loss of his family in the shipwreck, along with everything that he knew and was familiar with his entire life. I can't possibly imagine how difficult that would have been. Next, depending on what version of the story you go with, he has to see his mother brutally murdered in front of his eyes by a barbaric man on the lifeboat with him. That would be horrifically traumatic. After that, Pi has to abandon many of his precious, sacred beliefs in order to survive. He does not believe in murder, in eating meat, or in many other things that he has to violate in order to keep himself alive on the difficult journey he undergoes on the lifeboat. Having to abandon and violate the very principles that were so special to you would be devastating.
Then, at the end, if you believe the animal version of the story, Pi lost his best friend through his trials, Richard Parker. He left with no heistation, and that crushed Pi. He had to walk alone into a strange world, and start his life completely from scratch.
Those are just a few of the tragedies that occur in the book; good luck!