Self confidence is where you can believe that you can be yourself no matter what your friend/partner thinks. Personal growth is where you can do, wear, and enjoy what you like without feeling judged. Personal growth also allows you the freedom to not do what your friend/partner does. 

In an unhealthy relationship, your partner may be found to be controlling what you say and do. You may feel that every decision you make should revolve around what your friend/partner thinks. You feel that you won't be able to grow as a person without them.