Is anyone actually friends with their work colleagues?

when I was younger (18-21) yes, we'd go out together for dinner, drinks etc, had each other on social media, knew each other's partners. Then I had one "friend" who ruined it for me. I had been really poorly with flu, like proper full blown flu, horrible, so I took a week off work. The weekend at the end of that week was my partner's 30th and I'd planned a surprise weekend in Berlin for him. I was still feeling rough, but thankfully no longer feverish or achy, so we still went- it was a bday surprise, flights were booked, accom booked etc, it would have been silly not to go. My so-called "friend" at work saw my holiday pics on facebook and told the boss I had gone away to Berlin, and he decided that I'd obviously been skiving all week before and not really ill and so therefore he didn't pay me. I know that this boss was a horrible piece of work, but the "friend" also was horrible, and it cost me a weeks wages which meant I had to borrow money off my mum to pay rent that month. I do feel like I'm a better judge of character now in general, but, I no longer make close relationships with colleagues and certainly don't have them on social media, its too much of a risk when it can impact your wages that you need to live. I am friendly with my colleagues for sure, and we share things that aren't work related, like favourite songs or recipies etc, but I'd never get that close to someone at work again.