水乳交融 交融：融合在一起。象水和乳汁融合在一起。比喻感情很融洽或结合十分紧密。
彼：那，对方；此：这，我方。不分这个和那个。形容关系密切，交情深厚。
[all is common;be on very intimate terms;with no distinction between what is one's own and what is another's] 形容关系很密切
