if your the one who does the updates, writes the text and stories, and pretty much introduces members to the single girl and tells all the aspects of her life.. then your members will know when someone else is running it.
single girl sites arent just about the pictures, its more about the personality and atmosphere the site brings.. changes in attitude and personality will throw people off and could either really hurt the site.. or help it.
if your the creator of the site and the girl is just the eye candy, then weird as this may sounds, the surfers are not only attracted to the girls looks, but they also are attracted to your personality
if that changes, it will feel like a part of the site has died.
course, ive never actually ran a paysite.. im just throwing in my freudian 2 cents.