The "Wizard of Lies" actor, 75, married Hightower, 63, in 1997 after dating for a decade. They share two children together: 20-year-old son Elliott and 6-year-old daughter Helen Grace.
This isn't the first time the two have separated. De Niro filed for divorce in 1999 and engaged in a custody dispute over their son. The two eventually smoothed things over and the divorce was never finalized.
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In November 2004, the two renewed their vows in front of an A-list crowd such as Martin Scorsese, Meryl Streep, Ben Stiller, Tom Brokaw and others.
A representative for De Niro did not immediately respond to People.com for comment.
Page Six first reported the news.
(IANS)