1、He confessed himself to be unfaithful to his friends.
他承認自己對朋友不忠實。

2、Eg: it's immoral to be unfaithful to your girlfriend.
對女友不忠實是不道德的。

3、I think my spouse may be unfaithful to me.
我覺得我的愛人或配偶可能會不忠于我。

4、God told Hosea to find a wife, and told him ahead of time that she would be unfaithful to him.
上帝吩咐何西阿娶一妻子，并且事先告訴何西阿他的妻子將對他不忠。

be unfaithful to翻譯