So you're enjoying a piece of fiction, and things seem to be coming along nicely. The heroes have gathered the necessary plot coupons, acquired the Sword of Plot Advancement and cleared a couple of side quests. Now all that's left is the encounter with the Big Bad... ...But then, the narrative comes to a screeching halt, takes a sharp right-angle-turn and treats us to two of the characters having sex. Because apparently the romantic subplot has not received a satisfactory conclusion as of yet, and what better way to clean up that loose end than with an extended sex scene?