That's an interesting one Martin.
I've never had ‘friends’ in the generally accepted sense of the word - a fact that doesn't bother me too much - as I was a strange child always at home in my own company.
More so because of my job I've always been viewed with suspicion by others and those who have gone out of their way to become 'friends' I've had to view with suspicion, so it's a bit of a vicious circle for some of us.
I have, and have had, close acquaintances and colleagues without whom I wouldn't have been able to do my job - and I know and have worked with people from around the world - but thinking dispassionately about it I could never call them 'friends'.
The vast majority of my interaction with others stems from a professional requirement and, as I retire later this year, I can see myself becoming a recluse.

In fact the OOF is the only place where I have spent a lot of time communicating with other people where no real element of my profession is required to be involved.

So, although I prefer to plough my own furrow I am sensible enough to seek assistance when required, and when others need help I've disadvantaged myself to help them - that's why I became a copper in the first place, to help people, something I’ve done in spades.
Finally, irrespective of what the accepted definition of a friend is, what it truly means to each of us on here, there is only one person I can call a friend - my wife - she has stood by me through very difficult times, has taken the shit many copper's wives have had to as a matter of course, kept me from losing my mind and providing some semblance of normality in a (married) lifetime of professional turmoil - all while doing a dangerous, difficult and demanding job herself.