Why do people change?

Why do people have to change.I've recently come to realise that 90% of the people i know change for the worse.Why??Why does it have to be that way.The best years of my life was when i was 13 and 14.The things me and my friends used to do together.Wacky you might say,but wonderful.We had a wonderful bond.No one disliked anyone.No one bitched about anyone.No one had to prove themselves to anyone.Of course there were one or two minor misunderstandings here and they but they were all fixable.
But now,everyone's so different.There are so mnay people who's names i want to mention but i can't.The times we used to share,the bonds we created, nothing can ever replace that.Some are just so stubborn they won't even admit they're wrong.I'm not perfect and i know it.I myself make mistakes in this kind of situations.But i'm sure all my friends agree on one thing.I'm always say sorry.Eventhough I'm not wrong,I do it.Why?For the sake of friendship.Friendships which i feel are much to important to waste over a stupid misunderstanding.Unfortunately,NONE of my friends think that way.They would rather hold on to their pride and leave things the way it is.That's why I'm so fed up.
A friendship to me is very important to me.It is timeless.Unfortunately,i honestly have to say that I don't even have ONE true friend.I don't.I thought i did,but then i realised i didn't.So many people have hurt me in so many ways.They just don't realise it.Like I said in one of my previous posts,Its me thats the problem.it's how I take the ups and downs of life.
Lately I've been feeling very down because of a few things that have happenned.I'm no longer the same person.Sometimes I'm fine. I'm in an excellent mood.Another day I get into this awful mood where everything goes wrong and i feel like shooting everyone around me.I hate thsoe days.But then i feel that way practically 6 out of 7 days a week.Just ask my classmates.
SO back to the point of this post.peopel have really changed.I have too.For the better or for the worst i wouldn't know.I only have a few close friends.No more the Stacey who used to liek everyone and try to be everyones friend.Enough of that.All people do is hurt me.Stab me in the back,break my heart.Go fly a kite!Don't toy with my emotions.if you are never gonna admit your mistakes well then,i couldn't be bothered anymore.You know why?BECAUSE I'M CHANGING!Signing out.
P.S I do not mean all my friedns when i write this post.There are only one or 2 that i don't think of in this way.No names mentioned.