The requirement for using the ring to teleport to your partner in Heavensward areas is actually slightly different than A Realm Reborn areas.
We updated the Ceremony of Eternal Bonding website with this new information, but as many do not revisit that site I'd like to quote the text here for easy reference.
I hope this helps!*If your partner is in an area where it is possible to fly on a flying mount, you must fulfill the flight requirements in that area to be able to teleport to their side.![]()