two-time
verb [ T ] informal uk/ˈtuː.taɪm/ us/ˈtuː.taɪm/
脚踏两条船;对…不忠
to deceive someone you are having a relationship with by having a secret sexual relationship with someone else at the same time
I ended the relationship when I found out he was two-timing me. 当我发现他脚踏两条船时，就分手了。