2. Eternal Sunshine of the Spotless Mind
This film is unique in that it stars Jim Carrey, but is a romantic dramedy science fiction film that also happens to be critically acclaimed. It is also the second (and final) film on our list to be told in a nonlinear narrative. The story follows Joel and Clementine, a couple who have spent two years together, until things take a turn for the worse. Clementine contacts a company named Lacuna Inc. that has a technique for removing specific memories, and sets about removing every memory she has of Joel. After Joel learns of this, he is devastated she would do this sort of thing to him, and eventually decides to undergo the same process and remove all his memories of her and her betrayal. The only problem is that as the process goes on, it first re-asserts the memories he has before removing them, forcing Joel to remember the wonderful times he had spent with Clementine.
The Bittersweet Ending: Joel and Clementine meet once more on a train, having no memory of each other, and immediately hit it off. Shortly afterward though, they find the records of their memory wiping and realize that they tried to forget one another. Joel begs Clementine to start over, but she refuses saying the same thing will just happen again. Joel too realizes this, but doesn't care, and thus they give their relationship another try. While this may sound like an overall happy ending, it really has an element of mystery about it, unsure of whether their relationship will last, or if it will fail again. A brilliant way to end the movie really, and if you allow yourself to think about, very bittersweet after all.