Why do Prince Harry and Meghan Markle still refer to themselves as Duke and Duchess of Sussex?

ok.co.uk:

All eyes were on Meghan Markle and Prince Harry as they appeared at the Invictus Games over the weekend. The married couple appeared very loved-up throughout the opening weekend, and even shared a kiss on stage as Meghan, 40, introduced husband Prince Harry, 37.

But some people were left annoyed after Meghan welcomed Prince Harry up on the stage at the games. After a beautiful speech, the 40 year old said: "It is my distinguished honour to introduce someone that I think you all will be very excited to hear from.

Get exclusive celebrity stories and fabulous photoshoots straight to your inbox with OK!'s daily newsletter "He's the founder of the Invictus Games and the father to our two little ones, Archie and Lili.

Please welcome my incredible husband, Prince Harry, the Duke of Sussex." Reacting on social media at Meghan referring to Harry as the Duke of Sussex, one person wrote: "Prince Harry will suffice.