She wants to make her husband her slave. This is a common wish. I will assume that her husband has no idea that he intends to become her lover. You need to start by deciding if he is naturally submissive. The next time you have sex, put him in submissive situations, see how he responds. Tell him to kiss your feet. She smacks her butt. If he seems aroused, she uses pantyhose to tie him up. Tell him to call you Ama. Make it give you pleasure. Punish him if he falls short. Now you will know for sure if her husband is submissive. If so, every time you make love, you should take the reins in a similar way, but always up the ante. If she continues to enjoy it, then you are ready to become her Lover.
To make your husband your slave, you must now extend the Mistress-slave dynamic beyond the bedroom and into your everyday life. Before her husband leaves for work, arouse him sexually. Give him your underwear so he can think about you all day. Give him a list of instructions to complete by the time he gets home. Tell him if he doesn’t do them right you won’t let him have sexual gratification. Not allowing her to orgasm is the easiest way for a new Mistress to easily control her new slave. She will make him extremely lustful and willing to obey your every command.
Continue these “games” until you feel the time is right to talk to him seriously about your relationship. He will have come to himself and to you who is submissive; Likewise, you will have shown that you are dominant. He will also know that you enjoy the new arrangement because he will be having fun.
It is very likely that you are now aware of your own submissive side. Confront him and tell him, don’t ask, that you want to change your relationship. You want him to become your slave. At this point, he will almost certainly say yes, but he has done it in such a way that he gave her a choice in the matter. Then he can decide if he wants to become his slave. Nine times out of ten, the husband will say yes.