First thing to mention, observations below have become on my observations and do not specify all people or groups. Is it not unusual that one person rent a yacht or a sailboat for him self and beside boat it hire also a skipper.
Men of women who loves sea and probably does not have any one to go with them rent a sailboat for them self. Sometimes those individuals want to be on a boat for them self and need peace and quite away from any people.
In that spirit also time spend on the boat is function. Some people prefer quiet and do not speak with you/skipper most of time only when there is a necessary. However there are also people that are bored and would like to share with you every detail of their life.
There are a lot of cases when a rich widow or a husband that has lost his wife would still like to enjoy hobby that has share with his/her partner. When partner died, passion for the sport still exists and why not to enjoy this sport.
However I would like to mention when you are skipper to people of the opposite sex, people get lonely and sometimes they could expect more. In that case please keep the professionalism of the high level.