Other people can sway how you feel about someone, even from one friend towards another. You could have an influential person in your life saying you should hang out or talk to so and so anymore for whatever reason. And this other person has been a friend. How do you handle this?
If that other person is a true friend, try code #7 of the Code of Honor:
Never Permit Your Affinity to be Alloyed.
A definition of Affinity, taken from the book: Scientology: A New Slant on Life is "A degree of liking" and a definition of Alloyed would be to weaken or reduce the value of. People will try to have you not associate with people if they feel it would not serve their own ends. You really have to look out for this if you become a person of power and influence. Others can discourage your from being with good friends you grew up with, etc...
In short, YOU decide whether you want to be friend with a person or not. Don't allow others to decide that for you. And if you have a true friend, be a friend to the end !