The three major principles that guide relationship formation can be applied to many situations, and are even featured in American popular culture. Romance is a component of many movie plots, including the 2008 romantic comedy Forgetting Sarah Marshall. The two characters that fall in love, Peter and Rachel, display all three major principles. First, the two are in close proximity because Rachel works at the front desk of the hotel that Peter is staying at, so they see each other every day while Peter is in Hawaii. Second, Rachel and Peter display similarity and have things in common. They were both in serious relationships and got cheated on, and they both are at transition points in their lives. Third, they display reciprocity towards each other in the form of favors to maintain equity in their relationship. Rachel allows Peter to stay in a very expensive suite at the hotel free of charge, and Peter removes an embarrassing picture of Rachel from the men's bathroom at a bar, even though the bartender brutally beats him up for taking it down.
The three principles, proximity, similarity, and reciprocity, show that falling in love with someone is far from random. Although physical attractiveness may play a role in the probability of two people wanting to get to know each other, there's probably no such thing as love at first sight. In order for a relationship to develop successfully, the three major principles need to be acted upon to some degree.