cheat on

柯林斯词典

1. PHRASAL VERB If someone cheats on their husband, wife, or partner, they have a sexual relationship with another person. 不忠实于 (配偶或伴侣)[非正式]
I'd found Philippe was cheating on me and I was angry and hurt. 我发现菲利普对我不忠，我很愤怒并且受到了伤害。
2. PHRASAL VERB If someone cheats on something such as an agreement or their taxes, they do not do what they should do under a set of rules. 违背 (协议等)[美国英语]
Their job is to check that none of the signatory countries is cheating on the agreement. 他们的工作是检查以确认没有任一签署国违背该协议。