But this time, the man who married the girl "won" her after participating in an auction on Facebook.
Kok Alat, a business tycoon thought to be three times her age, beat four other men - including, reportedly, three high-ranking government officials - by bidding cars (three), cows (500) and cash ($10,000) to make the girl his tenth wife. A Facebook post dated October 25 shows a tall, solemn-looking girl standing next to an older man who is grinning victoriously.
On the face of it, this transaction is simply yet another example of a practice which takes place hundreds of times across South Sudan every year. While child marriage is technically illegal in the country, in reality local customs and traditions usually take precedence and it's common for girls to be exchanged for a "bride price" - which usually takes the form of cattle.
So is using Facebook to do the same thing really any worse?
Almost certainly. As Plan International's South Sudan Country Director George Otim put it, this barbaric use of technology is "reminiscent of latter-day slave markets." Publicising to millions what would otherwise have been an extremely harmful but nevertheless low-key community event made this all the more horrifying.
Putting it on Facebook brought more attention to the substantial riches to be gained from trading adolescent girls in this way. And it's entirely possible they were so significant this time because the sale went viral. As a result there is a very real risk that more families will put their daughters up for marriage, online or off, attracted by the gains on offer in a desperately poor country which has been blighted by a hunger crisis since 2013.
The government of South Sudan needs to show it is serious about ending child marriage, a deeply damaging practice. It should recommit to the five-year strategic action plan it launched in June, promising to end child marriage by 2030, and it should hold to account those government officials who appear to have participated in this auction.
But it is also clear that social networking sites like Facebook have a huge role to play in protecting human rights. Facebook allowed the offending post to remain on its site for a full 15 days. It removed the post, "as soon as it became aware." By that time the girl was already married. Attempts to reach her by Plan International's team in South Sudan have been blocked by her family.
Facebook cannot be blamed entirely for the orchestration of this "marriage". It's likely it would have gone ahead without the social media auction. But the company should recognise the damage done by their tardy reaction to this gravest of girls' rights violations. Voice of America, which broke the story globally, had their story out for three days before Facebook took action.
It is too late to save this girl from marriage, but action can be taken to stop millions of others being forced into a life-long relationship against their will and their best interests. Facebook has a role to play. This case - like the many others which have worried human rights activists - show that social media platforms need stronger reporting mechanisms and a more efficient process for responding to reports of violence or abuse. According to Facebook, they have 7,500 moderators to enforce their community standards, which include a ban of any form of human trafficking. Given there are 2.2 billion users, clearly they need more. It might also help if there were more local moderators based in countries like South Sudan, and more women - and if all received training in preventing gender-based violence.
Because this case is an example of violence. Against a girl who will likely spend the rest of her life with a man she didn't choose. This is first such case we've ever come across on social media. But will it be the last?