Luto translates to "mourning" or "grief". It's a strong and evocative word that isn't commonly found in every pop song, making it stand out.
In "Adiós Amor," the singer uses luto to express the profound sadness and despair he feels after his beloved leaves. He sings, "Pero mi cielo se vistió de luto," meaning "But my sky dressed in mourning," personifying his world as grieving the loss, which creates a powerful and memorable image of heartbreak.
Adios Amor is a farewell to a relationship that both people already know is over.
The singer says he saw this coming and refuses to make the goodbye harder than it has to be. He tells his partner none of this is her fault, that she deserves to be happy, and that he simply couldn't give her the life she needed.
Underneath the calm words is real grief, he says his sky has gone into mourning, but he chooses to wish her well anyway and let her know he's still there as a friend if she ever needs one.