Aferré comes from the verb aferrarse, meaning "to cling," "to hold on tightly," or "to be stubbornly attached to something." It's a strong verb that conveys a deep sense of persistence, often against better judgment.
In the song, the lyric "Me aferré a la idea de que esto no era el final" (I clung to the idea that this wasn't the end) perfectly captures the emotional struggle of holding onto a fading relationship. It's a powerful word that resonates with anyone who has stubbornly refused to let go of hope, even when faced with reality.
The narrator never moved. That is the whole song: "Me quedé en el mismo punto / Donde un día te perdí" (I stayed at the same point where one day I lost you). He took his heart's advice to give it time, and time did what time does, it went by, while she never came back. What makes this one land is that he refuses the excuse everyone reaches for after a breakup. "Y no fue orgullo, fue querer" (and it wasn't pride, it was love). He was not being stubborn. He genuinely believed something was still there.
The detail that hurts most is the hoarding: "Guardé lo poco que era nuestro / Como si aún fuera a servir" (I kept the little that was ours, as if it would still be good for something). Meanwhile she was already building a life somewhere else, far from all of it and far from him. By the last verse he has worked out who the problem was: "Que fui yo el que no supo soltar" (that I was the one who didn't know how to let go). And the title line, "Nunca supiste que te esperé" (you never knew I waited for you), is what makes the waiting worse. He did every bit of it in silence, so none of it ever reached her.