Where are these "Millions of women" you speak of? Asking for a friend. . .
If we limit our discussion to the U.S., then your "guesstimate" is overly optimistic. The actual statistics prove you wrong.
Table 3. Frequency of oral, vaginal, and anal sex in the past 12 months and past 30 days.
And it should be noted that these figures pertain to all men and women aged 18 to 70, not just married persons.
Regards,
Just last November on the day before my daughter's wedding, in my home county, a cadre of 21 Asian "masseusses" were captured in a sting operation. more here. There is nothing new under the sun, whether marriage or outside of marriage.