Sagrado translates to "sacred" or "holy". It's a beautiful word that adds a deep, spiritual dimension to the song's promise of love.
Enrique Iglesias sings, "Como fuego sagrado, te guardaré" (Like a sacred fire, I will keep/protect you). By comparing his love to a sacred fire, he's promising that his feelings are pure, eternal, and will be protected at all costs, no matter how long he has to wait.
Spanish pop star Enrique Iglesias goes all in on loyalty with "Si Juras Regresar" (If You Swear to Return). The entire track is built around a single, massive condition: as long as his partner promises to come back, he will wait forever. He claims he will trust her instantly: "Con los ojos cerrados te creeré" (With closed eyes, I will believe you). In Spanish, doing something "con los ojos cerrados" is an idiom meaning you do it completely blindly, without hesitation or doubt. He even promises to protect the relationship "como fuego sagrado" (like a sacred fire), which is dramatic, but it fits the mood.
Even with physical distance pulling them apart ("Aunque tú te tengas que marchar" / Even if you have to leave), he keeps his cool by holding onto specific thoughts, telling her "Sabré que bailas para mí" (I will know that you dance for me). He repeats "Pase lo que pase, aquí estaré" (Whatever happens, I will be here) and "No importa lo que tardes" (No matter how long you take). It is an absolute, stubborn kind of devotion, built on trusting a promise until time itself stops mattering.