The Royal couple initially met in 2016 on a blind date when a mutual friend set them up together but they manage to keep their relationship under wraps.
And as a result of their secrecy it took some months before the world knew they were an item.
At the time Meghan based in Toronto and was an actress with US drama Suits.
She had flown to London several times to see Harry covertly, while Harry was also said to have visited her in Canada in October 2016, around Halloween time.
Meghan had an Instagram account and used to post pictures of when Harry was in Canada with her, according to a report in The Sun.
During Halloween 2016, she posed alongside a smiley faced pumpkin as she wore a chunky knitted cardigan.
It turned out to be an important date because it was the last one they would enjoy before their relationship become in the public realm,
The couple were at a Halloween party and received a phone call that told them they should become concerned.
People in Meighan’s neighbourhood in Toronto hadn’t been bothered about their romance, so the couple thought they would go out and celebrate in disguise.
In unauthorised biography, Finding Freedom, royal reporters Omid Scobie and Carolyn Durand reported that the young in love couple enjoyed the “perfect” evening at Soho House.
However their evening was interrupted when they received a phone call which would change Meghan’s life forever.
They wrote: “They especially didn’t feel like spending Halloween weekend in hiding, as there was much to celebrate.
“Some four months into their relationship, they were madly in love and eager to take part in the fun of one of their favourite holidays.
“The evening of October 29, with Harry in town, the couple decided to go to a big costume party being thrown at Soho House in Toronto.”
Harry and Meghan wore Venetian-style masks so they could party anonymously.
It was funny because no-one knew they were in the company of a Prince.
Princess Eugenie, Harry’s cousin also attended the party with her now hubby Jack Brooksbank.
However their evening of frivolity was ruined when they got a phone call alerting them that a newspaper had discovered their relationship and was going to press with a story about it the next day .
In the book the authors wrote: “A cocktail or so into the party, they were both feeling relaxed, absorbing the Halloween spirit.
“It was possibly the perfect night out – until they received a call from one of Harry’s aides at Kensington Palace. It wasn’t good news.”
Harry and Meghan were said to be upset and angry that their secret was no more.
However now their relationship is out in public, they are married, have two children, have stepped down from the royal life and live in California.