cheat on

Idioms  

1. Be sexually unfaithful to, as in They broke up right after she found he was cheating on her. [Colloquial; 1920s]

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Example Sentences

Jenni told Shannon that Swan cheated on her frequently, and he had a condition which meant he would do things in his sleep that he was unaware of.

From BBC

Ninety-six people were prosecuted for attempting to cheat on driving tests or impersonate candidates in the 12 months to September last year.

From BBC

She says some women come in because they've been cheated on or had a difficult break-up and sometimes just because "they have anger coming from nowhere."

From BBC

All I can think is I’m in a wrestling match with all the great writers she cheats on me with.

From Los Angeles Times

In the handwritten letter - shown to the inquiry - he wrote: "When I said I loved you I meant it. I've never deceived or cheated on you."

From BBC