Colorín colorado is a classic Spanish phrase used to conclude fairy tales, similar to "happily ever after" or "the end" in English. It literally translates to "colorful, colored."
In this song, Justin Quiles uses it metaphorically to signify the definitive end of a relationship, stating, "Bebé, nuestro cuento se ha acabado, se cerró el libro, colorín colorado." This clever use of a childhood phrase to mark the end of a love story makes it both memorable and poignant.
Justin Quiles is here to tell us that some things just aren't meant to be, and that's okay! In "Colorín Colorado," he's closing the book on a past relationship with a surprisingly chill attitude. He starts by saying they're going "en contra de la naturaleza" [against nature], like it's rained a lot but the dam is still dry. It's a cool way to say some things just don't make sense or work out, no matter what.
He's pretty clear that "nuestro cuento se ha acabado" [our story is over] and "se cerró el libro, colorín colorado" [the book is closed, happily ever after] – that last part is a classic Spanish ending to a fairy tale! He admits he loved her, but "eso fue en el pasado" [that was in the past]. What's really interesting is that he says there's "no hay remordimiento, yo te tiro la mano" [no regret, I'll shake your hand]. He's not bitter; he's just moved on. He even jokes that if someone asks how she's doing, they should "vayan a tu cuenta... y que revisen to' tus estado'" [go to your account... and check all your statuses] because he has no idea! He's all about keeping things friendly, even suggesting they could still be intimate if they wanted, or just shake hands and be cool. No need for war, just happiness!