Rose Byrne, 39, has rekindled the engagement rumors after they saw her with a diamond ring on her wedding finger.
The Hollywood actress, who began dating American actor Bobby Cannavale, 48, in 2012, showed the huge flare as she attended Ralph Lauren's 50th anniversary show in New York on Friday.
She was first photographed wearing the same ring in 2016 while in her native Australia, but has never publicly confirmed that she is engaged.
Is Rose Byrne secretly engaged? The actress shows a diamond ring at New York Fashion Week … after revealing that she already calls Bobby Cannavale & # 39; my husband & # 39;
Last year, she told ES magazine that she often refers to Bobby as "my husband."
"He's practically my husband, so calling him is easier," he said.
"Formality is not an attraction for me, but we will do it some day, once you have children, I just think, why not?
Daily Mail Australia contacted Rose for comments.
Post-baby body: The X-Men star: Apocalypse showed off her post-baby body at the Ralph Lauren show in an archive dress from the designer's 40th anniversary collection in New York on Friday
Rose and Bobby, who have worked together on screen in Annie, Spy and Adult Beginners, share two children, Rocco, two and Rafa, 10 months.
Bobby was previously married to American actress Jenny Lumet and they share an adult son, Jake.
The X-Men star: Apocalypse showed off her post-baby body at the Ralph Lauren show in an archive dress from the designer's 40th anniversary collection.
Smitten: Rose started dating American actor Bobby Cannavale, 48, in 2012. The couple is portrayed at the Obie Awards 2017 at Webster Hall on May 22, 2017 in New York City.
He completed the look with striking red bombs by Gianvito Rossi.
Rose, who hails from Balmain in New South Wales, began performing at age 13 before triumphing in Hollywood.
In 2014, he starred in the hit movie Neighbors, with Seth Rogen and Zac Efron, and was announced as the face of Oroton, who entered the voluntary administration last year.
He also appeared opposite Oprah Winfrey in the 2017 television movie The Immortal Life of Henrietta Lacks.
Family life: Rose and Bobby, who have worked together on screen in Annie, Spy and Adult Beginners, share two children, Rocco, two and Rafa for 10 months