My condolences, Beach Boy. Never had lifelong friends, moved around too much, but longtime acquaintances are just as good methinks. Around me, people also die, or just drop out of the picture due to decrepitude.
Just ruminating: with your name, I think that Don Henley comes to mind for "Boys of Summer" before Roger Kahn. We did live in Hollywood in the 1960s, so I, too, remember the California blond girls and tanned and muscular boys riding waves. As is common with people, we like to hang on to good memories when we were young. " When we were young and full of life and not prepared to die" as in the song FERNANDO. Many other songwriters used that theme.
And then, we hope that "while we're not as good as we once were, we could still be good once as we ever were."
In the end, when we lose someone we love, time heals, but fond memories of times with the departed as much, after taking time out to allow ourselves to grieve.