expression
good fences make good neighbors; a hedge between keeps friendship green
Proverb meaning that even in close relationships, maintaining a certain distance or formality helps preserve harmony.
親友でも、近しき中に礼儀有りというから、あまり無遠慮にしないほうがいい。
Even with close friends, as the saying goes, 'good fences make good neighbors,' so it's better not to be too presumptuous.
A Japanese proverb of uncertain origin, likely adapted from a similar Chinese saying. The exact derivation is uncertain.