Mr Seaweed,
Friends come and go. No matter how hard you try to maintain good
relations, they will drift away. After school, you no longer in
touch, they have their own work place, you have your own, so the
common ground GAP between you and your former friends are
getting bigger. Its pointless.
So don't get depress over this, because its natural
progression.
If you serious about finding friends, get involve in religious
activities, where you can find friends who are your peers. But
nowadays, its hard to make friends even if you join hobby groupds
via facebook or other means.
Also this is a sign, for you to settle down, find yourself a
soul mate. When you have a soul mate, you will feel pre-occupied
and also have somebody to share your life with. You won't be
bothered about your drifiting friends.