How are people able to remain emotionally detached at work?

For example I know this coworker for 2 years now and he is very quiet and polite and helpful but his girlfriend works at our job and I have heard some stuff about him here and there like what his interests are but I still know next to nothing about him. He manages to come to work almost every day and stay quiet and detached emotionally from work and so I have been pondering about him recently. Thinking I wish I had whatever skill he has to be able to not attach to the jobplace.

Its like I can't help but form my identity as a person based on people i know including acquaintances from my job.

I am just sick of it. I hate how I can't emotionally detach. i have tried but I am extremely empathic - it means I feel and recongize others' every little emotion very easily just from as small an interaction as glancing in their eyes and those emotions make me insecure. If I see a negative emotion, I start feeling like that person feels such and such a way about me and I take it personally on some deep level. I hate it. I feel like I am doing life wrong. How do I detach?
How are people able to remain emotionally detached at work?
Post Opinion