Some people in life cant be replaced, but this cant be is never sure because our life is not permanent, then how can we even think of a person being permanent.
Every people part of your life is temporary, they are just for a while, for care , for support, for love, for friendship and forsake of you.
They have a role in your life, they come and they go, whats left behind is a life long lesson, thats the reason of me always saying that these people around are your teachers for little little time span.
You just need to understand that, and dont feel bad, if someone left you, because no one in life can be more important to you, then yourself.
Dont be addicted to someone, dont make someone oxygen for your life, that your own oxygen becomes poisonous to you.
But yes just love and respect them by the time they are in your life.