Resquicio translates to 'crack' or 'crevice'. It's a beautifully descriptive word that you won't encounter in everyday conversation, making it a great one to learn.
In the song, Ricky Martin sings about overwhelming confusion "en cada resquicio de mi corazón" (in every crevice of my heart). He uses this powerful poetic image to express that his heartbreak has seeped into every tiny, hidden part of him, showing a pain that is both deep and inescapable.
Ricky Martin's "Te Extraño, Te Olvido, Te Amo" is a classic power ballad about the emotional chaos that follows a big breakup. The singer is completely stuck. He says he's carrying around so much loneliness, "tanta soledad" [so much loneliness], and all he has left is a "foto gris y un triste sentimiento" [grey photo and a sad feeling]. He feels like he lost everything for this person, even his own identity, admitting he "aposté la vida y me dejé ganar" [bet my life and let myself lose]. It's a song for anyone who has ever felt like they can't move on.
The title itself, which means "I Miss You, I Forget You, I Love You," describes the impossible cycle he's trapped in. Every minute, he tries to get over them, but he says "ya no tengo remedio" [I have no remedy]. The memory is too strong. He goes from missing them, to forgetting them, and then right back to loving them all over again. He learned everything about passion from this person, but as he says, "no me enseñaste a decir adiós" [you didn't teach me to say goodbye]. He's having to learn that lesson all by himself.