Don't say goodbye.

The song depicts the protagonist's feelings of not wanting to break up after feeling the end of their love, wanting to go back to when they were close friends, and the heartfelt wish not to say goodbye.
The underlying theme of this song is "rain," which evokes tears, and the presence of "rain" appears in the lyrics, intro, and even in the final chorus, making it a piece that allows you to fully immerse yourself in the scene and worldview of the song.