By Monique Jessen
November 21, 2017
Credit: Monica Schipper/Getty

Meghan Markle arrived in London this week, and there's only one place she's staying — with Prince Harry at the palace.

Markle, who reportedly just wrapped her last season on Suits, has already semi-immersed herself into London life during many under-the-radar trips to the capital. And she is now preparing for a more permanent move across the pond.

"Harry has made no secret of the fact that he wants to marry her," a source tells PEOPLE. "She is the one."

During the last year, Markle has been spotted walking around Prince Harry's neighborhood in Kensington, carrying Whole Foods shopping bags (the health food store is a short stroll from Harry's cottage), picking up flowers and visiting a spa in Soho on the eve of Pippa Middleton's wedding. But it was an invite to Buckingham Palace for tea with the Queen last month that is most indicative of how serious things are between the two.

While their relationship has been moving along very quickly behind the scenes (they even chose their first Christmas tree together last December), the first public show of affection between the royal couple was at the Invictus Games in Toronto in September, when the two walked hand-in-hand into the wheelchair tennis event. A few days later, Harry was photographed kissing Markle when he joined her and her mother, Doria Ragland, in a private box during the event's closing ceremony.

WATCH: Kate Middleton and Meghan Markle Have the Same Lace Dress in Their Closets

On Markle's part, she has not shied away from expressing her feelings towards Harry, telling Vanity Fair in their October issue: "We're two people who are really happy and in love."

Hinting at the pressures they might one day face, she said: "I'm sure there will be a time when we will have to come forward and present ourselves and have stories to tell but I hope what people will understand is that this is our time."

Markle will live with Harry at his two-bedroom Nottingham Cottage in the grounds of Kensington Palace, where staff already know Markle. In a similar fashion, Prince William and Kate Middleton lived together at St. Andrews university and then at a secluded farmhouse in North Wales briefly before they wed in April 2011. There has been speculation that one day Harry will move into Apartment 1 at the palace which has 21 rooms and is currently the home of the Duke and Duchess of Gloucester.

While Meghan prepares to say goodbye to her chic one-bedroom apartment in Toronto (including potentially relocating her beloved dogs Bogart and Guy), Harry has been making subtle changes at home in order to make it more girlfriend-friendly. "It's not a question of if she's moving in," says the insider, "it's just a matter of when."

This Story Originally Appeared On People