Capricho translates to "whim" or "caprice". It describes a sudden, impulsive desire for something without a good reason, often seen as a fleeting or frivolous fancy.
In the song, Enrique Iglesias is desperate for reassurance from his lost love. He pleads, "Di que no es locura ni obsesión / Que no es capricho" (Say it's not madness nor obsession / That it's not a whim), hoping their connection is profound and real, not just a passing feeling.
Have you ever run into an ex and felt like there was still something there? That's exactly what's happening in this song. Enrique Iglesias is talking to a past love, and he's convinced it's not over. He sees something in their eyes, asking, "tu mirada dice estar arrepentida / Babe, dime si es verdad, o es sólo idea mía" (your look says you're sorry / Babe, tell me if it's true, or just my idea).
He remembers how close they used to be, singing that just "Ayer cabías en mi corazón" (Yesterday you fit in my heart). But then, they pulled away. Despite the goodbye, he's been waiting for them, telling them "Mi puerta siempre estuvo abierta" (My door was always open). The whole song is his plea for them to admit they feel the same way, insisting that life has shown them their love "No está acabado" (is not over).