I don't know - sure it is hurtful - but maybe they are lacking something in their relationship that he felt he needed.

Perhaps, he was trying to get "ideas" through the phone sex to make his sex life with his wife spicier? If the sex life is boring, then I can see someone being driven to the alternative; though, I think it is a huge waste of money. I mean, I know it sounds far fetched, but it is possible.

I wish them the best of luck.