shuǐ​rǔ​jiāo​róng

in complete harmony

水乳交融 shuǐ​rǔ​jiāo​róng
in complete harmony
literally like water and milk mixed together; describes a relationship that is extremely close or a partnership that is perfectly integrated

Frequency

Movie subtitles
0.180 per million appears in 0% of films
Written text
0.420 per million

Sources