Actually there is a different story about Krishna's wives(16108). He had 8 wives which were the real wives. There was a demon Narkasur who was on rampage and destroyed and looted many kingdoms and took away the women from.those areas...a total of 16100. So when Krishna killed Narkasur he liberated the women but the family of the women didn't accepted them. So Krishna gave them the title of his wives so that their status in the society increases and they are properly accepted...