Jane Austen wrote the "chick lit" of her day.  And when you look at her story lines, they are about marriage--mostly love, too, but not for every couple in the story.  Today's romance readers are the most voracious readers out there.  Movies seem to belong more to men--look how few roles there are for women in so many movies.  Oceans 11?  11 guys and one very attractive, young woman.  (OK, Dreamgirls is the exception).  But romance in the written word seems to belong to women (For us, by us?). 

Of course, it's possible to have a love story subplot in an adventure story, or an adventure subplot in a romance.  To each his or her own.  The good thing about books is that the reader brings so much of his or her own perception to the story.  And not all women demand or even want love stories.  Surely there are men out there who enjoy the love subplot (as opposed to the sex subplot) in Spiderman or Lord of the Rings, aren't there?  Do men read (or watch) Jane Austen?