知己知彼zhī jǐ zhī bǐ
know yourself as well as the enemy; be knows of the other as much as the other
原声例句
牛虻(原版)
" Don't betray yourselves till I move, " the Gadfly said softly and clearly.
“在我动之前不要出卖自己,”牛虻轻声而清晰地说。
恋爱物语
It's about knowing that no matter who you are in a relationship with, you are in with yourself and you can't betray yourself to make a relationship work.