Keep somebody at arm’s length
Definition 1 of 2
Pro Tip 1/3Professional Boundaries
Used in workplace settings to maintain professionalism and avoid over-familiarity. 
As a manager, she keeps her team at arm’s length to ensure fair treatment.
Pro Tip 2/3No Personal Details
To not share personal life or details; staying impersonal in the interaction. 
I prefer to keep my neighbors at arm’s length so our conversations stay casual.
Pro Tip 3/3Subtle Discomfort
Indicates a sense of unease or discomfort about getting too close to someone. 
After the argument, they kept each other at arm’s length.