Friends and then some.....

Have you wondered like i often do how friends, whom you feel so close to just drift apart?
I know people change, circumstances change but i still wonder......
My friend and i were chatting the other day and she was saying the same thing. we were lamenting on loss of contact with a close friend who recently got married. We were an inseparable trio,then she got married and lo, havent heard from her in months. I know friends fall in love, move to another city, get married and so on but that does mean friends need to drift apart???? yeah, i know i am being emotional but does it have to be that way? In the blink of an eye your relationship changes..... from being joined at the hip you become distant. do those people regret it too? do they miss their friends too or its just people like me.... impractical, sentimental who think this way?
There is the other end of the spectrum, where people try real hard to maintain the relationship even after equations change.But that breed is very rare. I hope i am one of them.
I remember friends whom i have shared my innermost thoughts with, laughed with, cried my heart out, shared their feelings, lend a shoulder to cry on.... now those friends are mere acquaintances and it hurts. I cringe at the thought of saying hello cos i remember the good old times and wish if they cant come back at least something better then a hello....
some practical soul will say maybe the relationship was not meant to be, life goes on.... yes it does, i know . But could we make the effort to keep friendships alive? could we make new friends and at the same time strive to keep the old?
I believe that in life we need enough money to survive, a comfortable home, a good job we love and the company of good friends.
could the good friends and the not so good/ distant ones please step forward??