You began acting proud the moment you looked into the mirror; if this is not pride or vanity, then what else is it?

Here, the poet catches the beloved in a charming, unguarded moment of self-admiration. Looking into the mirror, the beloved is completely enchanted by their own reflection and cannot help putting on airs of playful pride. The lover gently teases them, pointing out that if they truly claim to be humble and free of vanity, then how else can one explain this sudden, haughty swagger?