Romance novels have attracted considerable attention since their mass market debut in 1939, yet seldom has the industry itself been analyzed. Founded in 1949, Harlequin quickly gained market domination with their contemporary romances. Other publishers countered with historical romances, leading to the rise of “bodice-ripper” romances in the 1970s. The liberation of the romance novel’s content during the 1980s brought a vitality to the market that was dubbed a revolution, but the real romance revolution began in the 1990s with developments in the mainstream publishing industry and continues today. This book traces the history and evolution of the romance industry, covering successful (and not so successful) trends and describing changes in romance publishing that paved the way for the many popular subgenres flooding the market in the 21st century.
There is a review of this book, by Heather Schell, at the Journal of Popular Romance Studies. Here's an abstract: