I don't know is this is being too obvious, or redundant to any of the above, but my best friend is my partner. It was also the same with me and my late partner. They have both been the guy I was closest to, trusted the most, with whom I shared the most. If that hadn't been the case they would never have been my partner in the first place. And so long as we remain best friends, we will be together forever.
My partner & I are friends as much as lovers. I'll sometimes refer to others as one of my "best friends" but that naturally assumes my partner has first billing, before anyone else.
I'm very fortunate, mostly because of my partner, to have very many other friends. Recognizing I lack social skills myself, not being a naturally friendly & outgoing person on my own, I have deliberately looked to align myself with guys who have those skills I lack. Both my late & current partners were easy to identify as gregarious & popular men, and so that helped to endear them to me, as it has endeared many others to them.
paulflexes and others here have met my best friend, my partner, and I think can affirm what I say -- that his charm is irresistible, one of those "life of the party" guys you want to be around. And that I in turn ride the coattails of, and his friendliness rubs off on me when I've with him, he inspires me to try to copy him. But that's good, what I want, because the alternative, if left to my own devices, is to be left standing alone out in the cold.
So in a way I build my life around my friends. I guess I can do that now, being retired and having no career considerations or obligations anymore. I can associate with whomever I wish, and they are first & foremost -- my friends.