The romantic comedy is a genre of film based upon the hilarious premise that the course of true love never runs smooth. Typically they appeal to women and are almost solely responsible for unreasonably high expectations for male behaviour.
Male leads in romantic comedies will typically fall into one of 2 categories: People who act like Hugh Grant or people who act like Matthew McConaughey. With the former you have someone who is utterly inept and incapable of speaking to women in a lucid fashion, yet despite these impediments somehow manages to be charming. With the latter you have Matthew McConaughey or someone doing a convincing impression of him.
The female lead in romantic comedies often exhibits one very minor flaw, which perpetuates their single status. Whether it’s that she’s clumsy or that she’s a feminist, the male lead is able to see through and overcome the flaw.
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It’s a necessary requirement of a romantic comedy to include a part in which the either the male or female character (or occasionally both) stand in the rain. This is brilliantly demonstrated by rom-com stalwart John Cusack here:
There has been a recent trend in which the traditional traits of a romantic comedy are combined with traits of a stoner comedy. This is probably to allow Hollywood to cash in on both male and female markets, which typically want different things out of films:
Seth Rogan: Irresistable, whatever your gender