AI: Artificial Intelligence
The ending of the movie seemed to drag on forever but this was one of the saddest movies I saw as a kid. Even now, I still tear up here and there whenever I see it's on. If you've never seen the movie, you should watch it. If you don't want to, here's the basic plot
In the not-so-far future the polar ice caps have melted and the resulting raise of the ocean waters has drowned all the coastal cities of the world. Withdrawn to the interior of the continents, the human race keeps advancing, reaching to the point of creating realistic robots (called mechas) to serve him. One of the mecha-producing companies builds David, an artificial kid which is the first to have real feelings, especially a never-ending love for his "mother", Monica. Monica is the woman who adopted him as a substitute for her real son, who remains in cryo-stasis, stricken by an incurable disease. David is living happily with Monica and her husband, but when their real son returns home after a cure is discovered, his life changes dramatically.