Cappy made an excellent observation: Unconditional friendships are utopic. We all establish certain conditions to keep a friendship going, or starting a new one. It's only natural and human.
However, humans normally establish these conditions in freedom of conscience. Each one can decide for himself what are those conditions, and even change those conditions if he/she feels appropriate. The problem with Jehovah's Witnesses is: they don't have that freedom. They are subject to relentless undue influence via indoctrination and threat, in order to dismiss friendships based on criteria that they didn't establish themselves in freedom, but was imposed upon them, under threat of penalty. Such penalty may range from a vague 'displeasure from Jehovah' to a very real disfellowshiping.
Because their religious experience is served as a complete package to them, Jehovah's Witnesses don't have the freedom to accept the theology while choosing to reject what the religion dictates in terms of choices of friends. The total obedience demanded by the religious leadership implies that their criteria for terminating a friendship must replace any other criteria previously held by the individual Jehovah's Witness, or, in case of a born-in, that criteria becomes the only criteria that person has ever known. Thus, the way the JW believer deals with friends who no longer share the belief system or even slightly escape the religious norm stems, not from their personal choice exercised in freedom, but from the very nullification of their individuality.