Harry and Markle were noticeably absent from the service at St George's Chapel in Windsor, England.
L.A. friends likewise felt the "Meghan chill", Morton writes, saying Markle no longer had time for people she had known for years.
Just two years after Meghan and Trevor said "I Do", the couple's marriage sadly began to crumble.
Princess Zara Tindall, who is also pregnant, arrived at the chapel without her husband Mike Tindall and daughter Mia Grace.
Morton claimed "perfectionist" actress Meghan rehearsed how to drink cups of tea ahead of her first 2017 meeting with Queen Elizabeth.
'Prince Harry and Ms. Meghan Markle will invite 2,640 members of the public to Windsor Castle on their wedding day to watch the arrivals of the Bride and Groom and their guests and the carriage procession as it departs from the castle, ' the palace announced.
When it came to her and Engleson, Morton writes there were challenges other than the their long-distance relationship.More news: Baaghi 2 earns record 25.10 cr on opening day
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Meghan tweeted pictures of herself with the sportsman - whom she called "the best" - after watching him play for the New York Rangers, and revealed she had seen him on April 8 and 22, 2013.
"Trevor went from cherishing Meghan to, as one friend observed, 'feeling like he was a piece of something stuck to the bottom of her shoe.'"
She ended their marriage "totally out of the blue", sending their rings in the mail after walking out with a blender from their West Hollywood home and moving to Toronto.
Here are 6 surprising things we learned about the future royal from Morton's book, which is set for release in the USA on April 17.
She's set to Wednesday Prince Harry in a matter of weeks, but the spotlight has been turned on Meghan Markle's first marriage - and the abrupt and unusual way it ended.
The details about Meghan's life have been garnered from interviews with numerous sources including a former friend who describes her as a "social climber".
"She was always fascinated by the royal family", Priddy told Morton.
Prince Harry and Meghan Markle visit Catalyst Inc, Northern Ireland's next generation science park, March 23, 2018, in Belfast, Northern Ireland.