Trust & Betrayal

If someone trusts you, they are laying their vulnerability open to you. They might just be naive if they are kids but if you are an adult and you trust, you willingly open yourself up knowing that you could be hurt. 

But the reason you trust again as an adult is because you are courageous. It's an act of courage to trust and the reason is useful because if you trust, you open the door to reciprocity and you entice the best part of that person forward. 

But then when you betray someone then what you have done is you have taken the best part of them which is the part that will courageously trust with open eyes and you stuck a dagger in that. 

You have purposely damaged the best part of them and it's often people don't recover from that part of playing you. 

If you betray someone badly enough you can damage them, you can give them post traumatic stress disorder. If you really put your mind to it that's not just a psychological disorder; if you suffer PTSD you can face permanent neurological alterations that make you more neurotic, more sensitive to negative emotions, really for the rest of your life.

You can recover from it to some degree but stress will tend to reinstantiate PTSD. 

It's not just psychological but it's fundamentally a physiological damage. That's what you do to people by betraying their trust.