The bold part is not always the look. Sometimes it is letting him catch it.

She glances away slowly, not fast enough to erase what happened. Then she makes him carry the awkward part. If he walks over, she may lift an eyebrow like he started the whole thing. She may smile at her friend, as if this sudden approach was his idea from the beginning.

That little reversal protects her. He has proof, but not quite enough proof to feel lazy about it. He still has to decide.