Since Facebook came into our world, I have had 6 friends contact me 8-10 years after I got bored towing the friendship line. Out of the blue comes, "I think of you so often!" "I've missed our chats so much!" "I've tried to find you for so long!" "You fell off the map!" "I've missed you so much but couldn't find you!"
....and to this I say, "bullshit."
Whether it be an old email address that I still check occassionally or a mailing address I've had for over 10 years, or a past internet presence due to a column I wrote or charities I've helped, there has always been some way to EASILY reach me.
...then begins the long Facebook emails of their current troubles and woes (it's ALWAYS troubles and woes...), and of our great times together in the past to which I have no emotional attachment at all anymore.
Friendships are relationships and they take effort, and they are ALSO what makes life fun and worth living.
Life is busy for EVERYONE, but if you expect one side to make all the effort to keep in touch or make plans while you use the "so busy" excuse or can't be bothered to respond to emails, return calls, or get together, don't expect to keep that friend. And seriously, don't bother showing up 10 years later thinking they've given you a second thought---because guess what....
They won't.