One interesting observation is regarding jealousy. It seems to me when one is feeing jealous, any actions or words from the allege couple seem to be evidences to the accuser.
It can be a simple touch, an innocent smile and the accuser will go ‘There! There! That is the proof that they are having an affair behind my back!’
LEONTES Is whispering nothing?
Is leaning cheek to cheek? is meeting noses?
Kissing with inside lip? stopping the career
Of laughing with a sigh?--a note infallible
Of breaking honesty--horsing foot on foot?
Skulking in corners? wishing clocks more swift?
Hours, minutes? noon, midnight? and all eyes
Blind with the pin and web but theirs, theirs only,
That would unseen be wicked? is this nothing?
Why, then the world and all that's in't is nothing;
The covering sky is nothing; Bohemia nothing;
My wife is nothing; nor nothing have these nothings,
If this be nothing.
Act 1, Scene 2, Lines 334 - 346