Felber, who is known professionally as Attawalpa, posted "This Will Be Our Year" by The Zombies on his Instagram Story with heart and alien emojis on Sunday, September 26. Dunham had previously included lyrics from the song in a birthday tribute to her beau in June.
"Lena Dunham got married this weekend in London!" another source told Deuxmoi, adding that the "Lover" singer was "100%" there.
Dunham and Felber have not posted about their reported nuptials on social media. Swift has not posted about attending, either.
In April, the Tiny Furniture star told The New York Times that she was dating an English-Peruvian musician, but didn't name Felber. "It's been a few months. I feel really lucky," she gushed, noting he was "the greatest person I've ever met."
Last month, the duo made their red carpet debut at the Sundance Film Festival in London.
"When I was 3 weeks old in downtown Manhattan, I had no idea a baby was being born in England (Winchester, no less!) who would rocket into my life — wearing a lime green polar fleece snood — and challenge so many of my beliefs about myself and the world with magical abandon," Dunham wrote in her birthday tribute for Felber.
Last year, Dunham said that she had been briefly engaged to an unnamed ex-boyfriend who proposed with the lace of a boot after her split from Jack Antonoff.
"I'd just had a hysterectomy, I’d broken up with my boyfriend, I was in the process of breaking up with my business partner — I had no business buying a pair of shoes, [let alone] getting engaged," she told Cosmopolitan at the time. "Then I just went, 'You know what? I’ve been dating since I was 15 years old. I’m allowed to take a break.'"
Dunham had not previously announced an engagement to Felber.