Diabetes! I ought to know better than to hire anyone with a disease.

Escaping convicts! Counterfeit money! Guns! Devious ex-husbands! Fast paced dialogue!
It's not the latest action flick of the season people. It's the 1940 screwball comedy His Girl Friday!
Although this movie could be labeled a love story, it is not your typical guy-meets-girl-guy-falls-in-love-with-girl-the-feeling-is-mutual-the-end. The concept of love in His Girl Friday is not necessarily a romantic love. Love is portrayed more as a discovery of passion, in the case of Hildy Johnson, a rediscovery of passion. Instead of falling victim to the archetypal woman's role during that time period, the circumstances of the film allowed her to realize her place in the press. Cary Grant's character, Walter Burns, could be considered romantically in love with Hildy, but it is almost as if he is in love with chasing her and winning her over. Walter's passion derives from wanting to always get his way, a self-sufficient kind of love.
But no matter how hard you try to break down a person's reasoning for pursuing a partner, it all leads back to the most fundamental biological necessity.
Procreation.
So go ahead. Throw around your fancy explanations of the romantic psyche and analyze behavior until you reach that inevitable cycling effect. All of those details merely accessorize the fact that humans, nay, all living things, have an innate responsibility to further their species.
So the next time you're sitting dutifully at another "love" movie, popcorn in hand, eyes fixated on the screen, ask yourself, what are these guys really trying to achieve here? To the untrained eye, their paths may not seem to lead to reproduction for biology's sake. But sooner or later, all stories' paths diverge at the central checkpoint that is copulation.