Facebook might know couples are in love before they tell anyone

Facebook data scientists are able to predict when two people are heading towards a relationship, well before either of them updates their status. 

Soon-to-be couples share more posts in the 100 days before announcing their relationship on Facebook. Once the news is out there, posts immediately start to decrease.

The couples studied were those who changed their status from "single" to "in a relationship" and posted an anniversary date between April 11, 2010 and Oct. 21, 2013. People who do not list relationship status along with an anniversary were not part of the study.

The peak of posting comes 12 days before the relationship status change, when users post an average of 1.67 posts each day. By day 85, they're down to 1.53 posts per day. 

"Presumably, couples decide to spend more time together, courtship is off, and online interactions give way to more interactions in the physical world," Facebook data scientist Carlos Diuk wrote in a Valentine's Day blog post.

  But the posts they share take on more meaning as a relationship goes on. The interactions get "sweeter" and "more positive." It turns out people dramatically increase their use of positive words like "love" on the day or day after the status change.

Of course, Facebook tracks data on break-ups as well. In another post, Facebook's Adrien Friggeri reported that when love goes sour, Facebook interactions spike by 225 percent on the day of the break-up (or at least, the day of the status change). 

"This points towards people receiving support [from] their friends in times where they need it, whether it comes in the form of private messages, timeline posts or comments," wrote Friggeri.

The blog posts are part of a six-part series on love and Facebook. A Feb. 13 post offered advice on the best cities for singles. It said that of the 50 largest cities, five with the highest percentage of singles are Detroit, Los Angeles, New York, Miami, and Memphis, in that order. 

For those looking for love, Colorado Springs, El Paso, Louisville, Fort Worth, and San Antonio are the best bets for forming a relationship. In cities where it seems like everyone is paired up, reported data scientist Mike Develin, the impetus to become a couple is even stronger, and more relationships form. 

As for cities with the most singles, the highest ratio of single females per single male is in Memphis. San Francisco, meanwhile, has the highest ratio of single men for each single lady.