"For Couples, Time Can Upend the Laws of Attraction"

"At the start of the semester, the students pretty much agreed on who in their class was most desirable. But when they were asked again three months later, after spending a semester in a small class together, their judgments varied widely on who was hot and who was not.

“Perceptions of mate value change the more time that people spend together,” said Lucy Hunt, a graduate student who published the study last year with Paul Eastwick, an assistant professor of human development and family sciences.

“Sometimes you get that Seth Rogen happy story, where an unattractive person comes to seem more attractive to one person in particular,” Ms. Hunt said. “But the opposite is just as likely to happen, too. Someone can become less attractive.”

These changes in attitudes, Dr. Eastwick noted, should mean that there are fewer losers in the mating game, because everyone isn’t vying for the same Mr. or Ms. Right."
http://mobile.nytimes.com/2015/06/30/science/for-couples-time-can-upend-the-laws-of-attraction.html?_r=0&referrer=

And there are a couple more interesting studies in here - other impacts of people getting married after dating for longer.