她发现杰里米一直在欺骗她。

She found out that Jeremy had been ___cheating ___on her.

他承认曾与一位同事有染，背叛了他的妻子。

He admitted he had ___cheated ___on his wife with a colleague.

我绝不会背叛我的伴侣；这是关乎信任和尊重的问题。

I would never ___cheat ___on my partner; it's a matter of trust and respect.