Thinking Business... Or Not?

I was talking to a friend one day, and I was telling him that I can be friends with someone but still not like working with him/her (or vice versa), and he said that he thought he was the only one who thought that way. He said that you needed to think that way to be successful...

Another friend says he doesn't make friends in the work place. This is kinda extreme and lonely, I think, considering that you spend most of your time in the work place.

And then someone on the show Celebrity Apprentice said something like business is never just business, that business is always personal. Is this why so many contestants fight on the show? I don't watch it at all, but I've read that a lot of drama goes on in the show.

I have always been able to separate work from personal --- ALWAYS, and I don't understand how most people can't do this. It's like elementary, I think -- Business 101. I don't understand how some people can turn something work-related into something personal and carry it with them long after the job has ended.

Personal conflicts are much harder to overcome, and I personally don't even bother if the person has caused too much damage. However, professional conflicts are so easy to get over from. I can be in a heated exchange of opinions with someone about work and hang out with that person right after. I have also had colleagues with whom I had conflicts before but with whom I remain good friends up to now.

Even with the people I employ, I always make it clear to them that I don't mean anything personal when I criticize their work or try to correct them at something they're doing. Unfortunately, most of them took it personally and have long faded with my past. However, there are a few who knew how to keep the work separate from personal relationships and are thus still my friends up to this day.

I just think it's too much of a load to carry if you harbor grudges against a person due to something work-related. Is that part of the job description?