english
1
general::
Phrase(s): cheat on someone to commit adultery; to be unfaithful to one’s spouse or lover. • "Have you been cheating on me?" cried Mrs. Franklin. • He was caught cheating on his wife.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Be sexually unfaithful to, as in They broke up right after she found he was cheating on her. [Colloquial; 1920s]
American Heritage Idioms