Martin - who was also Meghan's makeup artist on her wedding day - said that the airing of the documentary had been a "relief" to close friends of Prince Harry and Meghan, who had witnessed first hand the toll the media scrutiny had taken on the royal couple.
"You can see it in her face when she reacts to [ITV host Tom Bradby] when he asks her that question," Martin said. "She takes a moment, she pauses, and then she goes into it, and you really see that in her eyes."
Speaking to Tom Bradby in Harry & Meghan: An African Journey, the mother-of-one appeared to break down when she was asked if she was okay.
"Look, any woman especially when they are pregnant you're really vulnerable and so that was made really challenging, and then when you have a newborn – you know…" she said, her voice cracking with emotion.
"And especially as a woman, it's a lot.
"So you add this on top of just trying to be a new mom or trying to be a newlywed it's, well…:
Brady then asked:
"And the answer is, would it be fair to say, not really OK, as in it's really been a struggle?"
Meghan softly admitted, "Yes."
Martin has been close with the 38-year-old since she ran her Tig blog - he even received cupcakes from Meghan for his birthday in September.
"It’s been tough," the Dior Beauty Consultant told CBS This Morning.
"Watching this documentary, it’s been almost a relief seeing her at a point where she can be honest about what’s been happening.
"All of us who have known, we just didn’t know what to do or how to help,
"But I feel like just putting this out there, it’s hopefully demystified a lot about what’s been going on over there."
CBS This Morning anchor Gayle King is also a close friend of the Duchess (having covered the royal wedding to Prince Harry and attended Meghan's New York City baby shower).
During the interview, King asked Martin if he would call Meghan "a weak person," to which he replied he replied, "No, not at all."
"I wouldn't either," King agreed, adding: "We should also say Harry and Meghan seem to be very in this together. That they are both supporting each other."