It is a very individualized definition. We know that it has something to do with genitalia. Physical appearance in our appearance-oriented society gets in the way of good relationships. One of the nice things about meeting people on the Internet is that you start the relationship on an intellectual basis and you get to know them before you actually see them. It is very individualized.
Some people like to have sex on a warm summer evening out in the woods.
Some people like it in a nice hotel. Some people like to have sex in the backseat of a car. The romance part is one of sensuality, warmness, luxury and all that stuff. Some people find it nice to have sex in a tent. We are very sexually active, so active that we have sex almost everyday.