All the jobs I've worked have been low-wage, where making friends with your coworkers means someone at work will have your back, at least in small ways.

Every low wage job I've worked at has been the same as well. One job I worked along side the department managers son, and we bonded over our mutual disdain for his dad haha.

What kind of job do you have? Something where people are all backstabbing career-climbers?

I've been in situations where someone who presents themselves one way at work, reveal themselves to be a totally different way out of work once they were comfortable.

I don't really want to get into a long winded story. Simple to say, in this one situation, the working and personal relationship was over, but while I might have been done with our "working relationship", our employer obviously was not. So I had to grit my teeth and "be civil" to a real chameleon of a human, knowing full well the depths of their narcissism and ignorant vulgarness.

Since their offense happened off hours and off work property, and "broke no laws", there was little my superior could or would do to address the situation. I was told he had a "conversation" with them, but little else. I thought about changing jobs, but they eventually moved on to "greener" pastures. This was many many years ago. I distanced myself from the "after hours" activities, and those eventually died off. I think my experience (which was no secret) poisoned that well.

Had this been a relationship formed outside work, I would have cut them loose and been done with it. It wasn't so simple unfortunately, thanks in part to the nature and relations of "work".