They turn her into a personal toy for fun:

Helty and Anne had a wonderful marriage, and even a better sex life. When they first got together, Anne let Helty know about her all time fantasy. One that she could tell nobody else, because she trusted no man. She was truly a submissive, and she wanted a man to dominate her, and take complete control of her. She craved to be spanked, to the point of not being able to sit down for a week at a time, wear a collar, and be called pet, slave, and sub. Helty was more than happy to oblige. He had never lifted a finger to a woman, so at first, this took some getting used to. After a little while, he began to do some research, buy toys, and go after Anne on the computer, and look up the sites that she looked up, to know exactly what it was she wanted. After a while being her dom, he brought up what his fantasy was. He wanted to have a three some. He never wanted to cheat on his woman, but have a three some, or even be with another woman while his woman watched.