Usually I have a problem with tragedies, because they seem to be manipulating the readers' emotions to bring out the tears, and convey the image of a great book. Shelley uttered, "Our sweetest songs are those that tell of saddest thought", and everybody else promptly got a formula for success. Of course every book manipulates the emotions, the problem with some tragedies is that they are also brazenly in-your-face about it. I find it a cheap trick to let one of the lead characters die at the end of the story, when keeping the character alive wouldn't have detracted anything from the story (my only grudge against Sholay, and suchlike).
Fortunately, Sparks' book needs Jamie to die; for how else is one to explain her peculiar devotion, her resolute miss-goody-two-shoes-ism? (Wow to me for that word!) One can feel that Sparks is tugging at one's hearts; that with the portrayal of excessive innocence on Jamie's part, he is setting the reader up for a crushing blow at the end. However, the cynical and suspecting reader is still not alienated and that is where the magic of Sparks lies.
[Prompted by Aparna's thoughts on the same book]