Couple announce their engagement on Facebook -- but their photo reveals another secret about their relationship

Always think twice before sharing something online because chances are you might reveal more than you actually want to.

One couple learnt this the hard way when they shared the good news that they were engaged.

However, they were puzzled when apart from people congratulating them, others were fixated on something else in the photo.

They had unknowingly revealed something else about their relationship to all their followers.

Click through the gallery above to see what it is.