Justin Theroux popped the question Friday and the actress, 43, happily accepted. Fans of the duo shouldn't be surprised – it's been a fabulous 15 months for Aniston and Theroux, 41, who first met while filming Wanderlust in May 2011.
Here's how they went from costars to engaged couple.
May 2011Aniston and Theroux are first spotted out together sharing a three-hour "casual dinner" at the Sunset Tower Hotel in Los Angeles. "They are great friends," a source tells PEOPLE at the time. "[Theroux] and Jen have spent a lot of time together lately."
Just a few weeks later, Aniston hosts a get-together to introduce pals Courteney Cox and Chelsea Handler to Theroux.
June 2011While in New York, Aniston and Theroux are spotted wearing matching rings that say each of their names.
The couple also dine with photographer Terry Richardson, who snaps a series of affectionate photos of the duo.
Aniston films an interview with James Lipton for Inside the Actors Studio and Theroux has a front-row seat. Throughout the three-hour interview, Aniston "would just look at him and give him a wink" in between questions, says a source.
The couple later join Aniston's Horrible Bosses costar Jason Bateman and his wife, Amanda Anka, for a double date.
During an appearance on Good Morning America, a glowing Aniston comments on her personal life. "I'm very happy. I'm extremely lucky, and I'm extremely happy," she says.
July 2011Theroux avoids the red carpet during Aniston's Horrible Bosses premiere in Los Angeles, but the couple reunite inside the screening and later hit Chateau Marmont with Cox and Handler.
While Aniston's being immortalized during her Grauman's Chinese Theater hand- and footprint ceremony in Hollywood, the actress is snapped blowing a kiss to Theroux, who sits front and center.
As she travels to promote Horrible Bosses, Aniston links up with Theroux in London.
After Aniston sells her Beverly Hills home for a reported $38 million, the couple begin to house hunt. But before she moves, the actress throws one last bash for her friends in L.A.
August 2011The jet-setting couple join Ben Stiller in celebrating wife Christine Taylor's 40th birthday in Kauai, Hawaii.
Upon returning to the mainland, Aniston and Theroux continue their search for the perfect home, but decide to rent a house together in the meantime.
September 2011The couple step out in New York City for the launch of Hoyle Jackson denim at Bloomingdale's 59th Street. "They were very cute. They [looked] like a real couple," a source tells PEOPLE.
As August ends, Aniston takes on a new role: director! While debuting Lifetime's Five, Aniston tells the press what she loves most about her life is "everything!"
October 2011While promoting Five, Aniston sets the record straight about her love life. "Rumor No. 1: I am not planning to get married any time soon," she tells Hello! magazine.
January 2012The couple head to Telluride, Colo., for 10 days, but return in time for a screening of Paradise Lost 3: Purgatory.
The couple join Bateman and Anka again for dinner, this time at West Hollywood's Fig & Olive.
February 2012During an interview with InStyle, Aniston says her relationship with Theroux has brought her to a "joyful and peaceful" place in her life.
Theroux also speaks to the press, telling New York magazine: "I am happy but I am not going to indulge it."
Aniston celebrates her 43rd birthday on Feb. 11, and Theroux divulges to The Ellen DeGeneres Show a bit about his personal life. "Ever since [Aniston] saw Zoolander, she's been obsessed with making me breakdance," he says.
Joined by Theroux and her father, John, Aniston proudly proudly receives her star on the Hollywood Walk of Fame.
March 2012During a radio interview, Aniston rates her happiness level at "10-plus."
April 2012Aniston and Theroux meet up with Tom Hanks and wife Rita Wilson for a double date at Katsuya Brentwood.
Aniston's ex-husband Brad Pitt and Angelina Jolie get engaged, but the actress is unfazed. "Jen moved on a long time ago and she is trying just to focus on her own happiness," a source tells PEOPLE.
After buying an 8,500-sq.-ft Los Angeles estate in February, Aniston sells her New York City apartment for $ 6.5 million.
June 2012At the MTV Movie Awards, Aniston takes home the award for Best Dirtbag for her role in Horrible Bosses. The couple parties alongside Aniston's co-star Jason Sudeikis at the Soho House in West Hollywood and spends the rest of the weekend together.
Days later, Aniston and Theroux head to Paris for a romantic getaway.
Engagement rumors begin to swirl when Aniston is photographed wearing a diamond ring and her gold "Jennifer" band (though, it turns out, she had worn this jewelry before).
August 2012Theroux travels to Wilmington, N.C., to visit Aniston on the set of her latest film, We're the Millers.
Then as part of his birthday celebration, Theroux popped the question and she said yes, they announced on the 12th.