不ふ忠ちゅう実じつ

noun

disloyalty; unfaithfulness

Refers to a lack of loyalty or faithfulness, often in personal relationships or duties. Somewhat formal or literary.

• 彼かれの不ふ忠ちゅう実じつが原げん因いんで、二人ふたりは別わかれた。

  His unfaithfulness caused them to break up.