"The study found that those people who remained Facebook friends with their ex-partner reported lower personal growth, suggesting that it was harder for them to move on. ....
As Dr Marshall pointed out, however, the study was correlational, and could not establish causal direction. For example, those people who are more distressed over a breakup may be more likely to view their ex-partner’s Facebook page."
http://www.brunel.ac.uk/sss/psychology/news-and-events/ne_229119
