By the time my DS was 18 he was pretty much responsible for himself. When he wasn't going to school, he paid rent. He was responsible for his own space (room and bathroom), his own laundry, his own cooking, etc... and he helped on the community space (he took care of the lawn and picked up after himself). He was responsible for his own expenses (car, entertainment, clothes, etc...) We didn't have a problem with how late his was out, usually work took care of making sure he was in early on weeknights, and if he was going to spend the night away from home, he'd usually leave a note for us so we didn't worry. At the time his girlfriend was under 18 and being that her mom didn't mind when she spent the night ( I checked with her first) I didn't have a problem with it.
By the age of 18 I fully expected him to be responsible for himself and start making his own rules - not expecting me to make them for him. He made some mistakes like staying out to late and not being able to make it to work the next day, or not getting his own laundry done - and he had to deal with the fall out from those mistakes (getting in trouble at work, less paycheck, not having clean clothes etc...)
By the age of 18 I fully expected him to be responsible for himself and start making his own rules - not expecting me to make them for him. He made some mistakes like staying out to late and not being able to make it to work the next day, or not getting his own laundry done - and he had to deal with the fall out from those mistakes (getting in trouble at work, less paycheck, not having clean clothes etc...)
How is it not courteous to for an adult to (legally) do X outside of the house, when the people who let you live with them find it immoral? How is it any of their business at all if it's not happening in their house?
) then he has to buy it. If we're taking everyone out to dinner, we pay. If he wants to spend the night elsewhere all we ask is that he let us know so we won't worry.