THIS IS BECAUSE THERE IS NO ENJOYMENT IN SIN,WHILE HE PASS THRUOGH THAT PAIN GOD WAS SEPARATED FROM HIM AND THIS IS TO SHOW THAT,GOD WILL SEPARATE HIMSELF FROM MAN WHEN HE NOTICE THAT MAN HAVE FALLING TO SIN,IF THE CREATOR CAN DO THAT TO HIS ONLY BEGOTTEN SON,THEN HUMANITY HAVE TO DO SOMETHING ABOUT IT.
ANOTHER REASON IS THAT WHEN HUMAN COMMITS SIN OR IN SIN ALREADY,IT GENERATE EMOTIONAL PAIN IN THE INNER MAN AND THE PHYSICAL AND EMOTIONAL PAIN CAN BE DESCRIBE AS THE TOTAL REMOVEAL OF ONES PEACE AND CONNECTION FROM HIS MAKER,AND THAT SIMIPLY MEANS THAT THE SINNER IS ALREADY ON ITS OWN UNTIL HE OR SHE DECIDES TO RECONCILE WITH GOD.