This is a ballad about being lost before the goodbye has even happened. The singer opens with "Yo no sé lo que haré cuando tú te vayas" (I don't know what I'll do when you leave), and the twist comes a few lines later: "Ya no sé lo que soy, ya no sé, y tú no te has ido" (I don't know what I am anymore, and you haven't even left). The heartbreak is all in advance, which is somehow sadder.
The title line, "Como si el destino me quisiera obligar" (as if fate wanted to force me), makes the breakup feel like a road with no exits, a "camino inevitable" (inevitable path). Then the chorus turns stubborn: he wants to change "esta angustia" (this anguish) and start finding "pedazos al mundo" (pieces of the world) again, "a pesar de mí, a pesar de ti" (in spite of me, in spite of you). That repeated line is the one to learn. A pesar de means "in spite of", and you will hear it everywhere.
One nice phrase for learners: "empiezo a deberle a la vida" (I'm starting to owe life something), a way of saying he feels he is falling behind on living.