Sometimes we are forced to withdraw from the lives of our friends. Sometimes our continued presence serves as an implication that we buy into their false realities. And while continued contact is always to be preferred, for love and correction have a greater chance through communication, the loudest voice can be a voice of silence. Voting with your feet, or withdrawing from a relationship that has become a lie, is a solid statement, and one that will be heard, even if grudgingly.
When contact becomes co-dependence, then absence can be an ongoing statement, an ongoing witness for truth.