“Weigel read dating-advice books from the 1800s and hundreds of articles on dating from teen and women’s magazines over the years, and she found two common themes: First, there is usually an older part of the population that perceives dating to be ‘dying,’ or, at least, as not being done ‘appropriately.’ Second, Weigel found that the way people date has almost always been tied to the market forces of their era.”