I have one who has been mine for forty years. We did lose each other once, but we found our way back. It was easy. And I will not loose her again, ever. She means too much to me.
Some friends I follow close, others I have hardly no contact with. Some I see when I can. Some I don't know if they really are my friends. Sometimes my family members are my friends. Some I tell secrets, and can ask about everything - some I wish all the best in the world, and am happy with when things go their way. Some I don't feel as close to. We just know each other. I don't always remember how.
How do you make friends? It's not like when you were little and could ask the kid next door if s/he wanted to play. Although I don't think I ever did that. I probably just checked the potential ones out from the corner, looking awkwardly serious, and even hostile. At least uninterested. But sometimes I was lucky enough to be chosen anyhow, by someone I really had had my eyes on. I might still do that - look awkwardly serious. And, when I finally start a conversation I know I try too hard sometimes. Small talk isn't one of my strongest skills. But this I share with many. We are just humans.
If you want a friend, then you have to be one, they say.