Zonzo is a colloquial and somewhat endearing term for "foolish" or "silly." It's not as common as other words for foolishness, making it stand out.
In the song, the singer repeatedly blames himself for being "zonzo" (foolish) in love, causing him to lose his partner. It captures a relatable feeling of regret over past mistakes made out of silliness or immaturity in a relationship.
This song, "Mi Enemigo El Amor," is a really relatable take on how love can sometimes feel like your worst enemy. Los Parras sings about the pain of love and how it can make us do silly things. He says, "El amor nos vuelve mensos" [Love makes us foolish], and that more love can lead to more jealousy and tears. He's suffering from loving too much and fighting to control himself, with doubts trying to kill him.
He admits to being foolish and cowardly, losing his love by making dumb accusations and saying stupid things. Even when his partner told him to leave, he stayed! The singer cries like a child to ask for forgiveness, but his partner's heart is hurt and offended, denying him affection. It's a real moment of despair, but then she comes back, crying, hugs him, and tells him his love is her destiny. He begs her to be reasonable and forgive his foolishness. It's a powerful story of regret, forgiveness, and the wild ride that love can be.