The friend gives it away first. Not him, not the room, not some dramatic reaction. The woman beside her sees the look last too long and suddenly stops watching the guy entirely.
Now she is watching her. Eyebrows barely up. Mouth trying not to smile. Maybe she goes quiet. Maybe her phone appears under the table and a message gets typed with one thumb.
That is the confirmation he was looking for without meaning to look for it. Someone who knows her caught the same thing: the slower answer, the hand left on the glass, the outfit not being corrected back into place.