separation anxiety

WordReference Random House Unabridged Dictionary of American English © 2025

separa′tion anxi′ety, 

1. Psychology the normal fear and apprehension expressed by infants when removed from their mothers or approached by strangers.
2. Psychology any similar reaction in later life caused by separation from familiar surroundings or close friends or family.

Collins Concise English Dictionary © HarperCollins Publishers::

separation anxiety noun

1. a state of distress felt at the prospect of being separated from a familiar or beloved person