Disloyalty (noun)

1. The quality or state of being disloyal; unfaithfulness to a person, duty, cause, or country.
2. Failure to support or remain loyal to a person, duty, cause, or country.

Origin:

Early 16th century: from old french desloialte, from des- (expressing reversal) + loialte loyalty.

Examples:

1. His disloyalty to the company was evident in his constant criticism of management.
2. Her disloyalty to her country was proven by her actions.
3. The disloyalty of the employee was a betrayal of trust.
4. The disloyalty of the politician to his party was shocking.
5. The disloyalty of the soldier to his comrades was a violation of military code.