The person who makes you fall in love at the beginning will be moved for the rest of your life. The movie tells the life story of Guo Xiaolu (played by Wang Chuanjun) and Su Lingfang (played by Wang Luodan), a pair of childhood sweethearts. They were forced to separate due to an accident in their childhood, and the letters that never arrived made the two embark on different life trajectories. The long-awaited reunion on campus and the passion of youth rekindled the love that had been separated for a long time. In the rest of their lives, the couple experienced repeated missed opportunities. Guo Xiaolu, who studies medicine, discovered the secret of eternal youth in despair, but as the lover around him grew old, the tacit promises left in his youth became an unforgettable regret in his fantasy life. Let time prove how much I love you.