But a few months after leaving the forces, Harry became hairy-er - sorry! - a look that made the youthful prince, 33, seem more grown up.
In the interview, the couple share personal details of how their romance began, the night Prince Harry proposed and the design of his fiancee's wedding ring.
Throughout her time in the public eye, Markle has garnered attention for her ability to start conversations on women's health issues and her India trip was no exception.
Jade Saylor, who is related to the future princess by way of her mother Roberta Markle Saylor's family, will marry Zachary Koller on May 12 in a small ceremony at her family's farm in Liverpool.
William is naturally accompanied by Kate and the two children, George and Charlotte.
Joining them will be a half company of 25 personnel from RAF Honington in Suffolk, where Prince Harry is Honorary Air Commandant.
Speaking about accompanying Harry and Meghan, he joked: "He might well give me a bit of abuse about my sword position or riding position but I think he'll be more excited by the fact he's pulled a cracker and will get to take her home".
"I can't imagine her being as interesting to people if she wasn't such a multifaceted person", said Fitz-Henley of Markle.
While most of the world is not lucky enough to hold an invitation to the royal wedding, there are still plenty of ways to watch the royal ceremony from beginning to end.
"Prince Harry was serving in Afghanistan at the same time as I was and I often wonder was he up overhead in his Apache as I conducted my patrol", he said. "She is very maternal and she was thrilled to meet George and Charlotte".
'So I think it's a really big gift for everybody that they're going through this process'.
By focusing her piece on the societal impact of menstrual stigma, Markle drew a direct line between the costs of shaming girls and their ability to grow up into healthy and educated adults.