The duet speaks of the infinite but tragic like involving Chang'e and Houyi, that are depending on the Chinese myth of the moon goddess, on which the film is based on. Amongst many artists who have recorded variations of "Always and Forever" is definitely the American R&B vocal group Whistle, https://always-and-forever73727.life3dblog.com/35898820/detailed-notes-on-always-and-forever-mine