Infiel means 'unfaithful' or 'cheater'. It's a direct and impactful word that immediately sets the tone for the song's narrative of betrayal and heartbreak.
In the context of the song, Marília Mendonça uses "Infiel" as a powerful accusation and a central theme. The entire song revolves around the consequences of infidelity, making this word not just a title, but the very essence of the story being told. It's memorable because it's the song's title and encapsulates the raw emotion of the lyrics.
"Infiel" is a confrontation, but not the shouting kind. The singer walks up to the other woman and says straight away that this is not a dispute and she is not there to provoke anyone. She found out about the affair a year ago and she has been looking for her since then, because today the pretending ends.
Instead of competing, she hands the man over. She calls him a prize that is worth nothing, says she put his bags outside and that he left crying, and tells the other woman that he is now her responsibility: "Você agora vai cuidar de um traidor." She is not losing him. She is getting rid of him, and she asks the rival to do her that favour.
The chorus turns to the man himself. She wants to see him living in a motel, she is throwing him out of her heart, and she tells him to take the consequences of what he did. Then comes the part she is most sure about. The other woman will end up playing the role that used to be hers, and in time she will be the one being lied to, because "você não vai mudar."
Underneath the sharp lines there is real hurt. She says the competition for love only served to hurt her. The song is less about revenge than about refusing to fight for someone who was never worth the fight.