Researchers at the University of Colorado surveyed 1,077 Facebook users to determine who people unfriend the most and how it makes un-friendees feel. “The most common reason for unfriending someone from high school is that the person posted polarizing comments often about religion or politics,” says Christopher Sibona, one of the researchers. This makes sense as religious and political leanings become more pronounced—and more divisive—in adulthood. “The other big reason for unfriending was frequent, uninteresting posts.” The survey also showed that the closer you were in school, the worse it feels to be unfriended.