Taylor Swift and Boyfriend Joe Alwyn Celebrate His Film The Favourite in L.A. with Emma Stone

Taylor Swift is Joe Alwyn‘s biggest fan!

On Friday, the singer, 28, supported her boyfriend of two years at the Los Angeles premiere of his new film, The Favourite.

“Taylor showed up at the afterparty and stayed until the end with Joe,” an onlooker tells PEOPLE of the couple whose relationship was made public in May 2017.

“She and Emma Stone were chatting up a storm,” the onlooker says of Alwyn’s The Favourite costar. “Taylor just stayed by Joe’s side the whole night.”

Swift previously supported Alwyn in September at the New York Film Festival premiere of the Yorgos Lanthimos-directed film also starring actresses Rachel Weisz and Olivia Colman.

Stone and Weisz play rivals in The Favourite, which follows Queen Anne (Colman) as she prepares for war with France. The royal, who reigned between 1702 and 1707, is advised by Lady Sarah (Weisz) until new servant Abigail (Stone) hatches a plan to become Queen Anne’s new trusted companion and “favourite.”

Alwyn plays a man infatuated with Stone’s character, though the feeling is not exactly mutual. The actress kicks him in the groin when he tries to kiss her in the hilarious trailer.

As of late, Swift has been by Alwyn’s side as his acting career continues to skyrocket. Her support comes after fans spotted the British actor at her Reputation tour stops, where he’s been seen supporting her from the audience.

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And recently, Alwyn, who rarely speaks publicly about his relationship, applauded his girlfriend for making her political stances known.

“I think it’s great, I think it’s important,” he told a reporter in October when asked about Swift’s encouragement for early voting and her endorsement of two Democratic candidates.

As Swift continues the international leg of her Reputation tour, a source told PEOPLE: “She seems to be in a great place both career and love wise. Joe is just an amazing boyfriend. He is very supportive. Taylor adores his family. She’s in a very good place.”

Swift will be performing in Tokyo, Japan, on Nov. 20 and Nov. 21.

The Favourite hits theaters on Nov. 23.