Wiktionary
cheat on
vb. (context idiomatic English) To be unfaithful to.
WordNet
Usage examples of "cheat on".
Whether he'd cheated or no' the first night, I could make sure he was seen to cheat on the Tuesday, when every eye would be on him.
She might kick his ass out and divorce him, but she wouldn't cheat on him-and only a fool would cheat on her.
He knew when a couple rented a room to cheat on a spouse, when a woman was hiding out from the guy who was as likely to put his fist in her eye as look at her.
All the guys had the same model, he said, so nobody could cheat on the weight.
He doesn't seem to be the kind of man who would cheat on his wife—.