I like Butterfly because it is dreamy.

It is a really beautiful song with a delicate and dreamy atmosphere.
The members' soft vocals blend with the gentle melody, drawing you into the song's emotion the moment you hear it.
The fear that the moment of love might disappear is delicately expressed in the lyrics.
If you listen to the song with earphones on a quiet night, the atmosphere feels even deeper, allowing you to listen to it emotionally.
If you like BTS's lyrical songs, this is a song I definitely want to recommend.