He’s too chicken-hearted to defend his beliefs in public.
他膽子太小，不敢在公眾面前為自己的信仰辯護。
Cheat on somebody:
給某人戴綠帽
例句：
She cheats on her husband.
她給她老公戴綠帽。
Have an affair with somebody:
跟某人有曖昧關系
例句：
You have an affair with him.
你和他有曖昧關系。
Two-time:
對(情人或者配偶)不忠
例句：
Are you sure he’s not two-timing you?
你肯定他沒有背著你另有所愛?
