We never remember in chronological order, especially when we’re going back over a failed romance. We start near the end, and then hop around between the times that were good and the times that left pain. People always say “start at the beginning,” but we didn’t know at the time it was the beginning. "500 Days of Summer" is a movie that works that way.
Some say they’re annoyed by the way it begins on Day 488 or whatever and then jumps around, providing utterly unhelpful data labels: "Day 1," "Day 249." Movies are supposed to reassure us that events unfold in an orderly procession. But Tom remembers his love, Summer, as a series of joys and bafflements. What kind of woman likes you perfectly sincerely and has no one else in her life but is not interested in ever getting married?