Responses
Fake friends stabbing you in the back means that you never see it coming.
However, the first half can be interpreted several different ways in my opinion:
A) For your true friends, you see them change and become the stranger that hurts you.
B) When your true friends try confront/betray/leave you, they do it openly without fear.
C) There are people who you have come to love so much that they are able to get close enough to you to hurt you before you would ever realize or suspect something was wrong.
"true friends stab you in the front, while fake friends stab you in the back"