Boy meets girl.
They fall in love.
They break up; cue the tears and depression.
The break-upees–in this case Noah and Tom–hope that their loved ones, Summer and Allie, respectively, will come back.
The heartbroken men try to reach their loves with some sort of letter correspondence: Noah writes letters to Allie every day for a year; Tom emails Summer hoping she will respond.
They reach a moment where the break-upees officially realize it is over: For Noah, he sees Allie’s fiance; for Tom, he sees Summer’s engagement ring.
The break-upees go through a resurrection: Noah works to fix up his dream house; Tom strives to give his life meaning and pursues the job of his dreams. During this period, they both find another girl, but they aren’t as important as their loves before.
Then they realize their dream: Noah finishes his house; Tom starts to apply for interviews. But they are still unsatisfied; they need closure.
They confront their exes again: Allie goes over to Noah’s new house; Tom sees Summer at Angelus’ Plaza. This time they are two different people.
While confronting the women who broke their hearts, they grasp something important: Noah realizes that he loves Allie indubitably and she is the person he wants to be for the rest of his life; Tom realizes that there is a such thing as fate, soul mates are real, and true love does exist.
Finally, the closing message for both movies are given–love does last forever. In The Notebook, Noah and Allie die in each other’s arms. In (500) Days, Tom meets someone promising–Autumn. Even though (500) Days isn’t as sappy, the message is still the same.