noun
neutral; noncommittal; neither close nor distant
Describes a relationship or attitude that is deliberately kept neutral, without strong attachment or detachment. Often used for diplomatic, political, or interpersonal stances.
彼はどの派閥にも不即不離の立場を取っている。
He maintains a neutral stance toward every faction.
隣
It's best to keep a noncommittal relationship with neighbors.
付かず離れず is a more colloquial expression with a similar meaning of keeping a moderate distance, but 不即不離 is a formal yojijukugo often used in written or formal contexts.
A yojijukugo composed of 不 (not), 即 (immediate, close), 不 (not), and 離 (separate, distant), literally meaning 'neither close nor distant'. The exact historical origin is uncertain, but it follows a common pattern of Buddhist-influenced four-character compounds expressing a middle way.