Had our first tent camping all by itself too. A family stayed for 3 nights and then simply left their tent for a further 3 nights, all on its lonesome. We have now taken it down and put it in storage until the family remember they have left something behind! We are now on day 6, poor lonely tent!
We don't mind if your tent is on site alone, whilst you gamble off elsewhere for a night, so long as we know. Tents generally need moving after 4/7 days so the grass underneath does not spoil and we think it reasonable to levy a 'tentcare' cost, should you not be sleeping-over in it, equivalent to one adult tariff for each night it is here alone.