The problem with a heart is that it can break be torn and leave us feeling deep pain and longing for what once gave us so much joy and happiness.
A man may try to avoid this by shutting down some of that joy when he feels it again, he may seek out fake joy in drugs and alcohol hoping that it will at least make the pain go away, he may finally find a partner that brings him joy but he may never allow himself to fully love him or her and will try to control that person to keep from feeling the pain he felt long ago when something he loved left or was destroyed.
A man may become so good at keeping himself from feeling pain in his heart that overtime he losses that connection to it. He loses that which makes him a loving human being and kills his heart. If he does this enough times he may no longer feel the aches and pains but he also no longer feels love and connection with those around him. This is the black heart.
He suffers a different pain. A pain of disconnection from himself and others. This pain strongly affects those around him although he may not notice it for a long time. He will wonder why he cannot relate to women, why his children find him cold and distant and why he is so uncomfortable around other men. He may feel very guarded around people and always ready for a fight.
In this distorted disconnected pain he instead seeks his happiness in things that he can own and control. And so there is a shell of pain around his heart and this is why it hurts to go there and reconnect in the beginning after it has been long suppressed.
The heart is a muscle and like every muscle it tears and rips, but each time it is made stronger through the process when it is allowed to heal. Just like the pain you feel when you work out so it is with the heart. The heart of the warrior feels the pain and knows he can withstand it. He feels it to heal it. He fearlessly lives though he may lose it all and in the grand scheme of things he will indeed. But know that the experience is always retained.
May you always be connected to your heart,