Have you ever had to end a friendship with a long time friend?

Yes.
Don't have time now but will return tomorrow and tell the story.

Sometimes you both just go your own way and where you are going is not the same place she is going. Other times there are reasons you become close to someone and when those reasons are no longer there or one of you does not need them any longer you go your separate ways.  Though I am the same person my concerns and interests have changed over time and sometimes they no longer interest me even if I try to keep up with them - there is no real enjoyment in their presence except old times.  Which can be enough I guess. 

Yep. He died.

No. I've drifted away from some, some drifted away from me - a couple have passed away. I've never formally had to tell anyone that we're no longer friends.

He lost interest or changed his mind.  Plus he is not talking, but it is obvious he has no intentions any longer.