An integral part of the process of appreciation, for it is an ongoing process, is to appreciate and to let go, allowing the natural processes of change to alter the nature of things and to be at-peace with this.
And so it is in your relationships when you appreciate and value other people. A genuine appreciation of another person will see you exercising this kind of allowing. You are prepared to perceive and acknowledge change and through this appreciation, you do not try to keep that person as they are. You allow them to change and you are at-peace with the changes.
When you create an identity for another person you are motivated to continually prove and justify that identity - to cling to your perceptions of that person. Because of this you may even be motivated to distort your perceptions of significant changes in that person, in order to maintain your preconceived view of them...