Desamarra comes from the verb desamarrar, which means to untie or unchain. It's a less common word than simply 'soltar' (to let go) and carries a stronger sense of being bound or held back.
In the song, Diana Fuentes asks, "¿Qué pasará si el cariño se te desamarra?" (What will happen if your affection unties itself from you?). She uses this evocative word to express the fear of love becoming unbound and slipping away, highlighting the deep emotional connection that might be lost.
"Qué Pasará" is Diana Fuentes and Vicente García asking the same question over and over: what happens to everything two people built together once the relationship ends?
The verses list what's at stake in specific, physical terms: the time spent sleeping on someone's chest, the rain, a memory tied to a beach, the length of her hair he loved. It's less a song about heartbreak in the abstract than a worried inventory of small, ordinary things that only mattered because they were shared.
The chorus keeps circling back to "qué pasará" ("what will happen") without ever answering itself, which is the whole point: when someone you're used to leans away, you don't get a clean resolution, just a list of unanswered questions about what's left.