I don't get it

I don't get it,
One day you my friend and the other you're not.
Obviously in the beginning our friendship wasn't worth a lot.

It takes that much after all we've been through.
You know what I understand because that's all you do.
One day I'm your sis and the next I'm an enemy.

What do you want from me?
I try to be nice, i try to be cool.
But in the end, we act a fool.

Then the next day we friends.
Sweetie make up your mind
Either it stays or either it ends.

I'm not going to stay and be used.
Because our friendship has been abused.
But I'm just gone chill and sit,
Because really I don't get it.