It's funny because both men and women see the opposite party as an extending of their desires, not necessarily full human beings. We have a culture where romance is based on ego and objectifying what we "should" have. It's not a lot of space for humanity left when you see romantic interests as potential fairy tale completers rather than the real, complex human beings they are.
This "means to an end" view to relationships by both parties makes flirting feel contrived much of the time and doesn't allow relationships to slowly grow over time.