well i would sure not kill the hero of the movie just to make the people cry. the ending could be happy. cause both where saved in the end. there was no point in killing him. but anyways i have not decided the end so can tell u much.
Though the ending was very touching but it is very heart breaking also. The director might have decided it to show the true love between them but, if something in the end had come like rescuing Jack and reunion of Jack and Rose.