The couple shares a son, Arlo.
Allison Williams is a bride-to-be! The same week that the 34-year-old actress made her red carpet debut with Alexander Dreymon at the M3GAN premiere, her proud partner took to Instagram to celebrate her and reveal their engagement news.
"Premiere of M3GAN with a screaming, laughing, cheering crowd. It's the ultimate fun scarefest," Dreymon, 39, captioned pics of him and Williams from the premiere. "I'm so proud of my gorgeous fiancée @aw."
"Congratulations to everyone who worked so hard on what will likely be a new cult hit," he added.
Williams has yet to speak out about the engagement news.
Williams and Dreymon began dating in 2019, after meeting on the set of the film Horizon Line, which was released in 2020. In April 2022, ET learned that the couple had welcomed a son, Arlo, that winter.
The notoriously private couple made their red carpet debut on Wednesday, with the Girls actress rocking a charcoal-colored sequined gown, and Dreymon opting for a black-striped suit, white dress shirt and black tie.
Prior to her relationship with Dreymon, Williams was married to tech entrepreneur Ricky Van Veen. The pair split in June 2019 after four years of marriage.