This mistress had no one better than her slave to experiment chastity humiliation on. The mistress stripped him naked and she had him wear a chastity device. She was trying to understand how to use it for fun as well as how to use it as a weapon to punish. In addition, she wanted to find out how she could use it to control a boyfriend or some other person.
Goddess Mel knew her boyfriend had a high sex drive. And she did not want him to cheat on her because she was going away for work for a long time. She did not want him to be tempted and find himself in the arms of another woman. So the mistress chose to make her man wear a chastity device so that he would not be tempted to cheat on her.