A study conducted by Epley and Whitchurch (2008) noted that people often see themselves as more attractive then what they may in fact be. In their experiment on self-recognition, the researchers had 27 Caucasian participants pose for a photograph which was then cropped and morphed into 5 less attractive faces and 5 more attractive faces then the actual photo. After a two to four week period, the participants were invited back to view their photo. They were told that they would be presented with a series of images that had been modified from their original photo. Whilst viewing the 11 photos in a random sequence the participants were asked to point to the one they believed to be their actual face. As predicted, the majority of participants selected one of the more attractive faces as their own, proving a self-serving bias exists when recognising one’s attractiveness.
An article in the Journal of Family Psychology showed that heterosexual relationships in which the man is slightly less attractive than the woman exhibit better interpersonal relationships. The interpretation - or at last one of them - is that one of the things that less attractive men offer to attract more attractive woman with a broader range of choices is greater attentiveness, willingness to listen, etc.
For a more formal and comprehensive treatment of using market and economic principles in an attempt to understand key elements of heterosexual relationships, see Baumeister and Vohs (2004) It always generates lots of reactions (ranging from amused to heated) and provides a good opportunity for talking about what one looks for or doesn't in good theory -- ability to parsimoniously explain a range of existing phenomena, ability to generate new testable predictions, use of principles that are "independently motivated" (developed for purposes other than for explaining the phenomena in question), etc. It also provides opportunities to talk about things like naturalistic fallacy errors and the temptation to evaluate psychological theories (provisional and testable descriptions of nature) by the way they make us feel or the social ends they might or might not serve." Here's a link to a related article.