This hairstyle along with many other unreleased hairstyles, (I've only found these hairstyles for female human and norns) has been spotted many times on the Gemstore along with some unique NPCs, such as White Mantle Cleric, Lake Doric villager, Mistwalker Ilia and many others.
Why wont you, ANet, release these hairstyles to us players? They have been datamined for a long time now and for a time they were bugged in the hairstyle kit where you were able to use these unreleased hairstyles, including a normal simple ponytail, wedding hairstyles, flower in hair-styles and others.
They've been in the game for a long time now, ever since HoT launch I believe as some NPCs started to use these kind of hairstyles.
Anneeeeeet pleaseee, release these too! I mean, they're ready to go and they look so pretty!
I would appreciate if an ANet employee answer to this
PS; while you are at it, release the dress on the 1st picture too!