Clavo literally means "nail", but it's used here as part of a famous Spanish proverb. The saying "un clavo saca otro clavo" is the equivalent of "the best way to get over someone is to find someone new".
In this song, Alejandro Fernández cleverly twists this idea. He sings, "Porque con ese clavo sólo abrirás otra herida" (Because with that nail you will only open another wound), warning his ex that a rebound relationship won't heal her, but will only cause more pain. It's a powerful metaphor that turns a common saying on its head.
Sé Que Te Duele is a dramatic pop confession where Alejandro Fernández and Morat flip the usual breakup script. Instead of begging for another chance, the singer calmly says “I know it hurts” while pointing out every reason the relationship is truly over. She loved his voice, the fame, the romance, but never really loved him. Now that he has finally walked away, she is left chasing empty nights and harmless lies that only leave new scars.
Yet this is not a cold goodbye. The chorus admits that watching her lost and alone also stings, because he once gave her everything— every kiss, every note, every ounce of fight. The song balances pride and lingering tenderness, showing that letting go can ache on both sides even when it is the only way forward. If you have ever broken free from a one-sided love, this track will sound like your heart setting itself free, guitar strings and all.