As Father has a very strong human feeling, it was a difficult thing for him, too. Father told me that Heavenly Father trained him in that way. Think of King Saul. God ordered him to destroy the enemy camp completely, but he brought the spoils back to his camp. Saul couldn't obey God's order.
Separation is very severe.
When Heavenly Father told Father to cut off the human relationship, Father must have really had a difficult time since he is such a deep hearted man. First of all, unity with God and, secondly, the unity between the adviser and the person being advised. If a leader gives a member advice and he doesn't have a good feeling towards the member, it is because there is not good unity between them. When the leader can't love that member, this shows that God is encouraging them to become one centering on His will. The point is that you must be closer to the member and the member also must feel closer to you after you talked with him.