Should we arrest Donald Trump for prostitution in this case? I'm pretty sure his young, nubile wives did not marry him for his good looks and great hair. Moreso for the cash and other gifts he provides. So you can legally do all the same things that a prostitute and her John do as long as you don't ever verbalize what you're doing. Non-verbal communication is the key. The verbalizing's not the best part anyway.
“I’m pretty sure his young, nubile wives did not marry him for his good looks and great hair.”
In your scenario, why did they marry him at all then? They could have just charged him a fee, done the requested item(s), and left.
There is a purpose in marriage. And if all it is is whoredom, then no one would marry.