Young And Unmarried Girls Wearing Wedding Rings

There seem to be a new trend in town: girls who aren't yet married now buy and wear wedding rings. I've seen a few cases. 
 
But I really wonder the motive behind this development. Could it be to ward off unwanted advances from men; a manifestation of low self esteem; or vain deceit? Ladies, would you be kind enough to explain the possible motive behind this ridiculous invention? Because it's become a lot harder to differentiate between real and fake wives, and married and unmarried ladies.