I recently booked through singlescruises.com. More than 10 cabins were booked for this particular cruise. They had two leaders, "cruise directors." A male and a female..... they did not have their own cabins; they each shared with one of their paying customers (they did not pay for the cruise or shore tours, at least that is what I was told by one of them; I suppose that is part of their compensation...)
I would like to suggest that when considering booking through an organized singles tour, look around and see what the same cruise would cost you if booked independently.