(an instance of) defecting , e.g. to another political party (or its leader), to another religion etc

abandonment

(a feeling of) uncertainty

lack of faith, conviction; questioning

deliberate deception

deception

(an act of) disloyalty or being unfaithful, especially to a wife or husband

disloyalty to an obligation

the act, result, of being treacherous

disloyalty, dishonesty

(the serious crime of) betrayal of one's country or ruler

disloyalty