Well, I had a best friend through my childhood and teens, but as we grew into adulthood, she became an attention seeking nut we grew apart. Now, I have a couple of very close girlfriends (people with whom I share most things and meet maybe once / twice a month for a sleepover and good catch-up), some secondary friends (we meet for drinks and a chat maybe once a week, but no heavy conversation) and then acquaintances (people I see and chat with at social events, but we would never actively arrange to meet up with). TBH, I'm not the most sociable of people, so I like it this way (mostly).
Sometimes (like if I watch some sappy Sit-Com) I feel that I am missing out on the whole 'live in each other's pockets close' friendship (I grew up watching Friends), but in reality, I know that I would find that kind of friendship suffocating.
My DP, Mum, Dad and sisters are my 'best' friends, or, the people I will talk to about anything and never feel nervous around. Aside from them, I stress about meeting people, even the 'close' friends. I adore my two close girlfriends, they adore me, but sometimes I still stress over meeting them. I come across as confident, witty, charming (have been told this, not being arrogant) but inside I am usually a social wreck, which is why I don't let many people get close. It is often easier that way.
Hexagonal 'I've met a couple of people in adult life I'd like to be best friends with too'. Me too. But I'm always to nervous / inept / terrified of rejection to pursue it.