Best friends forever or never is firstly depend on the way you treat them.This is the fact if we are respecting someone,we also expect respect from one to whom we are respecting.If we do not get what we deserved so we may end the friendship.Nature towards your best friends describes how long the friendship is going to be continue.
Trust is another important factor which describe the best friends are going to be forever or never .Never breaks your friend's trust or else is going to be very difficult to get it back.May your friend is giving again another chance even you cheated her but remember the trust she showed earlier is not going to be shown by her in future.She will not trust everything that you tell her and she may find you diplomatic person.She will have a fear or will be afraid that her best friend can cheat her again and break her trust once again and therefore she is not going to share everything with you.

If you have jealousy with your best friend then it is almost sure that your friendship is for never as you did not feel happy when she succeed in something moreover you feel jealous.

But.if you have a good nature with one another,trust which you never break,no jealousy then congratulations because your best friend is forever....