unfaithful
🇺🇸
/ʌnˈfeɪθfl/
🇬🇧
/ʌnˈfeɪθfl/
not loyal or true to a spouse or partner, especially in marriage
He was unfaithful to his wife and had a secret relationship with another woman.
他对妻子不忠,与另一个女人有秘密关系。