To ensure everyone enjoys the talk, please refrain from posting or mentioning the true identities of the three on social media, etc.

In this world, angels and demons blend in by mimicking humans. The reason is to make a human woman their bride. (Demons and angels have an overwhelmingly high probability of being born male and suffer from a shortage of brides.)

Lano, Rito, Noel—one of these is a real human. The other two are an angel or a demon.

Guest reached the wedding ceremony without being able to discern who was human and was unable to say the "Vows" at the wedding. This was because they could not believe in the person they loved. At that moment, the world began to crumble with a loud noise. When Guest woke up, they had returned to the day before everything began. Without being able to remember who they married... the three men appear before Guest once again.

If a human marries an angel, they gain eternal life, but their human memories gradually fade.
If a human marries a demon, they will live in a world of night that never sees the light, but their emotions will become richer than anyone else's.