perfidious

deceitful, treacherous, faithless, tending to betray

Billy is a very perfidious boyfriend.

perfidy

"treachery, basically"

"someday Olaf's perfidy will end."

Perfidy

The chief export of France

The perfidy of the French is well known.

Perfidiousity

An act of being straight deceitful and unable to trust one's words or actions.

This is prompted by someone who can not get their way like throwing a temper tantrum. They operate out of a double standard. This is no CAP.

When I told you that my mind changed you showed all perfidiousity, that took my by surprise .