Earlier this month reports surfaced Pitt was dating the German model, 27, as the pair were spotted together on holiday in France.
It has since been revealed Poturalski is in an "open marriage" with well-known German restaurateur Roland Mary, whom she has been married to for eight years. They share a 7-year-old son together.
Mary is reportedly on his fourth marriage and doesn't mind his much-younger wife dating the Hollywood superstar.
"They are still married, but you could describe their relationship as an open marriage," a source told the Daily Mail.
"He has been married several times and has five children. He is not interested in negativity or jealousy."
In fact, Poturalski reportedly met Pitt at her husband's restaurant last year.
Pitt was in Berlin promoting the Quentin Tarantino movie Once Upon a Time in Hollywood at the time.
"Brad Pitt has been coming to Borchardt for years. He knows Roland, and Nicole was at the restaurant when he came to celebrate his new film," a friend of Poturalski told MailOnline.
"Brad was introduced to Nicole and she passed him her number."
The Polish-born model then flew to Los Angeles a few weeks later, and she and Pitt began hooking up. They were pictured attending a Kanye West concert in November.
The pair are yet to comment on their romance.
Pitt's new relationship comes as his court battle with ex Angelina Jolie continues to play out.
Jolie is trying to get the judge tossed from their divorce case, claiming the jurist hasn't been forthright enough about previous dealings with one of Pitt's lawyers.
Pitt's lawyers noted in responding court papers that the judge is the one who Jolie picked to marry them in 2014.
