In the field of social psychology, the idea that people are more likely to form successful relationships with and express liking for people whose level of physical attractiveness roughly equals their own.
Example: A man of average attractiveness goes on one date with an extremely attractive person, and then another with an average-looking person. He finds he likes the average-looking date more.
Grinnell, R. (2010). Matching Hypothesis. Psych Central. Retrieved on July 4, 2015, from http://psychcentral.com/encyclopedia/2009/matching-hypothesis/