Discover the story of the song > Brick – Alex G

The protagonist is saying that even though their romantic partner may think they don't know when they are lying, the protagonist actually always knows. Every time their partner tells them something untrue, it creates a division between them and the protagonist, like a brick in a wall. The protagonist is certain that their partner is lying and they are aware of it. This pattern of lying and the resulting division makes the protagonist feel distant from their partner.