Robert De Niro's girlfriend Tiffany Chen called his ex-personal assistant a 'nasty bitch' and compared her to 'Single White Female'

• Tiffany Chen, partner to Robert De Niro, took the stand Thursday in U.S. Federal Court in Manhattan.
• Chen testified that De Niro’s former personal assistant Graham Chase Robinson was obsessed with him.

The gender discrimination case against Robert De Niro stemmed from a pitched battle between his new girlfriend and his "office wife" over who would gain domestic supremacy of his Upper East Side townhouse, according to testimony in Manhattan federal court on Wednesday.

The "Goodfellas" actor's latest squeeze Tiffany Chen, 45, took the witness stand in the afternoon to testify against Graham Chase Robinson, 41, the star's former executive assistant, who sued the two-time Oscar winner for $12 million in a federal discrimination claim.

Robinson, who worked for De Niro's vanity company Canal Productions for 11 years, claimed that the "Raging Bull" star was an abusive boss who wanted her at his beck and call 24/7.

De Niro hit back with his own countersuit, charging that Robinson plundered the petty cash drawer and racked up the company's American Express bill buying groceries, expensive meals, hotel bills and more than $30,000 in Uber and taxi fares over two years. The actor also claimed she stole five million frequent flyer miles.

Robinson's lawyers called Chen to the witness stand hoping to portray her as a jealous girlfriend on a vendetta.

Robinson was fixated on De Niro, Chen alleged

Chen, wearing black leggings, a ponytail and light brown cowlneck sweater with matching high heel boots, told the court that she tried to get along with the long-time assistant, but said it became clear pretty soon that Robinson was a "mean, insecure and territorial girl."

"She used every opportunity to get into the space we were in," Chen told the court, comparing Robinson’s behavior to the obsessive villain in the 1992 thriller "Single White Female."

"She was worried that I was going to get in between his relationship with her," Chen told the court.

Chen, a Golden Gloves boxer from an internationally recognized martial arts family, met the actor during the 2015 filming of "The Intern" in which she played a Tai Chi instructor.

They started dating while De Niro was still married to his former wife Grace Hightower and she moved in with him in 2018 around the time of his divorce.

The couple still live together in the Upper East Side townhouse with their daughter and 15 dogs, Chen said.

She portrayed Robinson as perpetually angry, sabotaging Chen at every turn.

"I started to see from the very beginning that she was very angry in a certain way. Very mean and bitter. She was a hot mess all the time," Chen said.

Chen said that Robinson was so controlling that she was the only one who knew about the security system of De Niro's home and would come into the house when the couple was away to rearrange the furniture. Chen said Robison would come into the couple's bedroom and unplug her chargers and throw her electronics on the floor.

"She thinks she's your wife," Chen wrote in an email read in court. "I'm tired of her rearranging things and throw my stuff on the floor in chaos whenever she decides she wants to be the 'lady of the house.' It's bizarre and it really has to stop."

Chen said on a charter flight she took alone back from Antigua Robinson deliberately did not arrange for an in-flight meal for her, an omission that the girlfriend said felt deliberate.

On one occasion, Chen said that Robinson felt so entitled in her role as scheduler and personal handler that she was openly contemptuous of De Niro.

"I swear to God, he's so fucking annoying," Chen said Robinson once told her. "He annoys me all the time."

When Chen said Robinson failed to act over a toxic mold infestation at the townhouse, she sought to limit her duties to the production company only, keeping her away from the couple's home.

"I have had it with Chase's bullshit," according to Chen's email read in court. "Chase is a straight up Nasty Bitch."

In another Chen promised, "I'm going to fucking give that bitch what she deserves."

De Niro was an insufferable and exacting boss, Robinson testified

Robinson, who grew up on the Upper East Side and went to the private Saddle River Day School and then to the boutique St. Lawrence University, also took the stand Wednesday describing the relentlessly needy De Niro as a demanding, abusive boss.

She denied ever having any attraction to the actor and denied having any designs on coming between him and his girlfriend.

In her lawsuit, she said he underpaid her, relegating her to menial household tasks and even had her scratch his back. She claims she was forced to quit in 2019 when she pulled down $300,000 a year.

"He got frustrated quite a bit," she said.

Robinson said that De Niro would call her five to 10 times a day from 5:30 to sometimes late into the night.

One time she was out with friends at Nobu at 10:30 at night and he called her asking where she was, what she was doing and who she was with. He then asked her to bring him a martini from the restaurant's bar.

"He came downstairs. He was in his pajamas and slippers and I dropped it off in a plastic cup," she said.

Robinson said that after she got home De Niro rang again at 1 a.m.

Her testimony is expected to continue Friday morning.