How's that?
Their actions betray their true perception of themselves. If they were actually confident, they would not feel diminished by rejection or experience a sense of loss - they would simply remain grounded in themselves. Since they are not confident, they feel an anxiety when their hidden perception of self ("I am not good enough") is exposed by Sonyab's rejection. And the way they attempt to dampen the anxiety of rejection is through downgrading her; by stripping her of a perceived higher status, her rejection is rendered meaningless.