Nah, I'm pretty sure that's just a Chinese Whisper that originated from David McCandless work in data mining breakups on Facebook. It can tell you what the most popular day to breakup is, but it can't predict when a couple is going to breakup.
However that said it probably is possible to predict breakups with communication data. You could probably even do it with an iphone app, breakups tend to follow certain events (like drop in respect, distancing, etc.) that can detected in vocal patterns.
There is a (YC?) company that analyzes your GMail and tells you which of your friends you haven't been in touch with, in recent times. I'm forgetting the name right now. But we all know that Facebook has an edge over GMail in terms of personal data, and they can certainly do it.
Hmm. I can see an app waiting to be built there. :-)
However that said it probably is possible to predict breakups with communication data. You could probably even do it with an iphone app, breakups tend to follow certain events (like drop in respect, distancing, etc.) that can detected in vocal patterns.