Forever doesn't exist

Sometimes there are things that happen to you that makes you curious as to why is this or that so....I've just been thinking of some stuff like:
1) What is "forever"?
when it comes to relationship or friendship, people say or tell each other, "I want to be with you forever; we're going to be together forever etc.... whereas I personally think nothing lasts forever. of course this is just my opinion and everyone else have their own opinion of what "forever" is. People always end up either leaving or changing and that at the same time changes our view of what forever is or should be.
I think instead of promising to be there forever, lets just say "I'll be there for you as long as I can or live"..yeah yeah it's almost the same thing as saying, "I'll be there for you forever" but at the same time there's a difference to it; you are promising to be there for the person as long as possible..not forever because "forever" doesn't exist!
2) Friends that use friends:
I might be late in the game to noticing this, but some people preferably called "friends" only call, text, or remember you when they need you to do them a favor. When things are going all good and peachy, you don't exist in their world until everything goes sour then all of a sudden bam! there they are calling your phone; and you're sitting right there wondering, "why in the world is she calling me?" So I have decided that those "friends" that call me whenever they need a favor would never and I repeat never get it! that's a promise....