The Bierman phenomenon

The theory that the aftereffect of prolonged time spent in the presence of an associate, leads to a higher chance of developing a romantic interest in them. The affection could be mutual or one-sided.

Unsubstantiated studies show that this phenomenon also presents itself when an individual's thoughts are consistently filled with any type of reference to the opposite party.

Guy 1: Dude, I think I love this chick.
Guy 2: Could just be the Bierman phenomenon. Spend some time away from her. Think about something else. The feelings will probably go away.