She a public relations director for Ralph Lauren and had dressed Markle for a press day for Suits.
An Instagram shared by the now bride on June 30 thanks von Westenholz for her help.
Following this Instagram snap, Markle posted a number of images on the social network that can now be seen as clues of a blossoming romance with the prince.
The couple has also since confirmed to the BBC that their two first dates took place in London, around that time, before a secret holiday in Botswana, where Prince Harry was working.
Asked about whether she'd set up the first date, von Westenholz did not deny it.
"I might leave that for other people to say [who it is]," she told the Daily Telegraph.
"It's a great story and I am sure they are going to be very happy together. I am just happy they are really happy. They are great together."