What does it mean when your best friend criticize you on everything you do even though you know your are doing what must be done?
I'd go with 1Direction_Mars and love2dance123's answer
Maybe you need to either compromise or find a new best friend..........
It means that your friend doesn't understand you like you think she or he does.
In my personal opinion it means that your friend thinks she's better then you and that you aren't good enough for her so she's trying to make you be more like her by criticizing you.
She thinks she's better than you. That's not a friend you want