水乳交融 交融：融合在一起。象水和乳汁融合在一起。比喻感情很融洽或結合十分緊密。
彼：那，對方；此：這，我方。不分這個和那個。形容關系密切，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] 形容關系很密切
