A complete timeline of Tom Hiddleston and Zawe Ashton's relationship

The gala took place in London, England.

Years later in an interview with Tatler magazine, Ashton said that she and Hiddleston "had done a reading together of the central scene, at a gala for Harold Pinter's birthday," which led to her getting an offer to be part of the revival of Pinter's "Betrayal," costarring Hiddleston. 

The play opened on March 13 at the Harold Pinter Theatre in London, following about a week of previews.

The play is centered on a married couple named Robert and Emma, played by Hiddleston and Ashton, respectively, who become entangled in a love triangle with Robert's friend, Jerry (Cox). 

The actors were friendly at the event, posing for photos together and hugging. 

Their "Betrayal" costar, Cox, was also in attendance to support Ashton. 

Previews began at the Bernard B. Jacobs Theatre on August 14 and the show opened on September 5. 

During the Broadway run of "Betrayal," the actors celebrated Halloween by dressing as popular Marvel characters.

Hiddleston, who's played Loki since 2011's "Thor," and Cox, who stars as Daredevil, dressed as each others' characters.

Meanwhile, Ashton donned a Captain Marvel costume. Coincidentally, years later, Ashton would get cast in the "Captain Marvel" sequel. 

They were spotted watching a women's singles match between Johanna Konta and Karolina Pliskova as part of the annual tennis tournament. 

This marked the first time the couple had ever shown overt PDA before. It's still unclear when exactly they started dating. 

"Betrayal" was nominated for four awards at the 74th Tonys: best revival of a play, best actor in a play (Hiddleston), best scenic design of a play (Soutra Gilmour), and best direction of a play (Jamie Lloyd).

Hiddleston and Ashton walked hand-in-hand while posing for photographers on the red carpet.

Their engagement was confirmed by People magazine and Us Weekly four days later. 

"I'm very happy," the actor told the Los Angeles Times, without elaborating further. 

Ashton wore a sparkling, off-the-shoulder tulle gown, baby bump visible, at the New York screening of the film "Mr. Malcolm's List" at the DGA Theater.

"Tom and Zawe are loving being new parents and are filled with joy," a source told the publication. "They have been having the struggles of new parents and aren't sleeping much but are thrilled."

They wore blue outfits as they watched Novak Djokovic and Carlos Alcaraz compete in the gentlemen's final. 

Ashton will play a villain named Dar-Benn in the upcoming "Captain Marvel" sequel, titled "The Marvels."

The actor told EW that her casting "led to some incredible conversations about his experience being part of this franchise for over a decade."

"One of the main takeaways from our conversations was: 'What you put into Marvel, you get back.' He said, 'If you go into this with an open heart and a great work ethic and just want to provide an amazing experience for the fans, you'll have an amazing experience on those sets.' He really empowered me in that way," Ashton said of Hiddleston. 

Hiddleston, who's all too familiar with the struggle of wearing a superhero costume, also suggested that Ashton ensure she had enough zippers on her costume to make bathroom breaks easier. 

"Which is very good advice, I realize now," Ashton said.