Libreto literally translates to 'script', like the written text of a play or movie.
In this heartbreak anthem, Jesse & Joy use it metaphorically to call out a partner's repetitive and predictable excuses. By singing "Tú, libreto de siempre tan predecible" (You, the same old script so predictable), they express that the relationship feels like a tired act they are finally walking away from.
Mexican pop duo Jesse & Joy bring us the ultimate "pack your bags and go" breakup anthem in "¡Corre!" (Run!). Joy sings about knowing a relationship is completely dead before the other person even speaks. The coldness is in the tiny details: hugs that have zero warmth ("Me abrazas y no siento tu calor" [You hug me and I don't feel your warmth]) and a partner who finishes her sentences just to stay in control ("Siempre tienes la razón" [You are always right]). She calls his behavior a tired script ("libreto de siempre" [same old script]) and compares him bluntly to an old dog that can't learn new tricks ("el perro de siempre los mismos trucos" [the same old dog with the same old tricks]).
Instead of begging him to stay, she pushes him out the door. She sings "Así que corre corre corre corazón" (So run, run, run, sweetheart), telling him that since he was always the fastest runner when problems showed up, he should sprint away one last time. Notice how she uses "corazón" here; it literally means "heart," but in Spanish, it works like calling someone "sweetheart" or "darling," except here it sounds sharp and fed up. She tells him to take whatever he wants, but he won't get a single tear from her ("mis lágrimas jamás te voy a dar" [I will never give you my tears]). By the final line, after so many repeated goodbyes, she is done writing verses for him and simply shrugs: "la verdad me da igual" (to be honest, I couldn't care less).