He cheated on her for years, but she never sussed.

他有外遇多年了，但她从来没有察觉。

《牛津词典》

I thought Megan dumped him after he cheated on her.

我以为他不忠后就被梅甘甩了呢。

youdao

He cheated on me once, when we first started, with this girl who had air-conditioning at her place.

在我们刚开始好的时候，他骗过我一次，跟一个家里有空调的女孩出过轨。

youdao