The couple released a statement saying that the split was entirely amicable and by mutual agreement.

这对夫妇发表声明称离婚完全是友好的、双方自愿的。

The relationship was ended by mutual agreement.

【mutual】双方协议结束了这种关系。

By mutual agreement she's leaving at the end of the month.

经双方同意，她将在月底离开。

" Well, there are things which are placed beyond the pale of discussion; and I thought this was specially so, and by mutual agreement."

“我说，有一些事是不容讨论的；我想这件事尤其如此，并且这是我们双方都同意了的。”

Think of them like states in the US: the state lines are decided upon by mutual agreement, and a city can be in one state or the other.

州界是由双方协议决定的，一个城市可以位于其中一个州，也可以位于另一个州。