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

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

Mariano can’t stop thinking about his beloved, deceased wife, who cheated on him 40 years ago but never said with whom.

From The Wall Street Journal

A pub quizmaster sparked a "massive whodunnit" after he outed a team for cheating on social media but refused to name them.

From BBC

Phypers accused Richards of cheating on him with another man and of scaring his parents when she arrived at their Calabasas home in early August to retrieve her dogs, among other allegations.

From Los Angeles Times

This past spring, OpenAI offered students two months of free access to ChatGPT, evidently hoping to lure them into buying paid subscriptions that will help them cheat on their homework, papers and tests.

From MarketWatch