The only thing constant is change. I have had to move places since my childhood due to my dad's job. Even I hated change. But at one time, I had to put up at a place for 5 years. I realized that I am so used to changing places and people that I started getting bored of that place and environment.
I think people change because their priorities change. At every point in life, you must have noticed that we also tend to change. Even our food preferences change. One must learn to adapt to change.
One more thing, if you had friends who had been bad to you,may be it is because you must have chosen the wrong ones. I have moved a lot of places, still I am in touch with few. It is better to go out of a person's life before they ask you to.

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Grandma's rocking rings

This ties back with the friends and acquaintances thing again, is someone who is bad to you because of a change really your firend or just an acquaintance?

I feel a good friend does stick on for a long time,even if that means exploring new common grounds to keep up the friendship.

with time...with new life experiences....may makes people change in their ways of thinking....interacting.... i may happen a good friend may change....it could be for the better or for worst....

umm... well as everybody agrees that things change all the time... once somebody told me this n till today it still stays with me all the time "the world is subject to constant change".....if yr friends change for the better then its fair enough that u should b with them... bt wat if they change for the worse????u cnt jus turn yr back on them and walk away???wat sort of an image they wud have of u,...that u were a bad friend???i guess, wats best is that if ever they change for the worse , they will gradually grow away from u, in the sense that they may try to influence u so that the whole gang wud b alike.now, u have to b strong n firm nt let know that u r in no way going to change to become one of them.... that wil either have an impact of them n they'l realise wat they'v done or they will simply move away from u themselves....this in a way solves yr problem... u didnt chase them away, rather they chose their own path...

We are living in a materialistic world where everything and everyone is changing...still my best friend and i are still together and we are here to help each other..

change is part of life(AND I LOVE CHANGE) and it keeps things interesting!! could you imagine if nothing ever changed how boring life would b???? accepting change and being able to adapt to change is a hard skill to master but once you get used to it you will start to enjoy life more!!

Unfortunately we can not do a lot of things against all this changes!! The world is developping and people are changing! For sure sometimes it's not for the better!! Personally I choose my friends very well, some of them are still there since I was a little girl at school and now that I'm a big one who is working! The first persons who will call me at the beginning of the week-end to know what i'm doing it's them! It's not everybody who is changing thanks god..

Yea, you are right, things have been changed with the changing of time, everything is changing and taking the wrong turn.
We cannot do anything about it, as it is the people themselves changing it all.
And if it continues, thre will be a time when the word "friend" itself would disappear!