I lived with her family too for a few months when I had a falling out with my folks. When we eventually broke up (due to distance, a KU LB, etc.), her folks checked on me weekly and told me they still see us being together in the end. They took care of me like one of their own. If I was a crap human being during that time in my life, i could see it being a issue. I don't think they were too worried about a 18 year old virgin, captain of the baseball team, top 10% of his class, and a national honor society member dating their daughter. Go kick rocks somewhere.
About common, did you guys have internet in said small town? rough ridin' do some research.