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. 不忠實於 (配偶或伴侶)[非正式]
I'd found Philippe was cheating on me and I was angry and hurt. 我發現菲利普對我不忠，我很憤怒竝且受到了傷害。
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. 違背 (協議等)[美國英語]
Their job is to check that none of the signatory countries is cheating on the agreement. 他們的工作是檢查以確認沒有任一簽署國違背該協議。