Aoki Lee Simmons, 21, and Restaurateur Vittorio Assaf, 65, Split: 'Kimora Was Concerned' (Exclusive Source)

Aoki Lee Simmons and Vittorio Assaf have ended their brief romance.

Four days after PEOPLE confirmed the model, 21, and restaurateur, 65, were spending time together, a source close to the Simmons family tells PEOPLE that they have parted ways.

"Not only is it 'over', it was never a thing," the insider tells PEOPLE. "Aoki is learning to navigate her private life in a public sphere. And that can be difficult. However, Kimora was concerned to see her daughter in that kind of relationship due to what she herself went through."

A rep for Aoki could not be reached for comment. Page Six was first to report news of the split. 

On April 5, a source close to Aoki told PEOPLE that she and the Serafina group founder were "spending time together and enjoying each others' company,” adding that the couple met while vacationing in St. Barths, a favorite Simmons' family travel destination. Photos at the time showed the couple sharing intimate moments on the beach.

Aoki is the youngest daughter of model and mogul Kimora Lee Simmons, 48, and entrepreneur Russell Simmons, 66. The 21-year-old is an up-and-coming model and has worked with top fashion houses including Tommy Hilfiger, Michael Kors, Dolce & Gabbana, Monse, Lacoste, Tory Burch and Kate Spade. 

She began modeling for her family's Baby Phat line and Just Fab as a child and in 2021, made her runway debut modeling for Pyer Moss Paris Couture. She’s appeared on the covers of Teen Vogue, Rollacoaster and Flaunt and has been featured in outlets such as Vogue, Huffington Post, The Cut, Essence and Complex.

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In addition to her modeling career, Aoki graduated from Harvard University at just 20 years old. To celebrate the achievement — as well as her 21st birthday and Teen Vogue debut — Aoki’s mom Kimora threw her daughter a lavish party at Soho Grand's Club Room in New York City. Kimora and Russell’s eldest daughter Ming, now 24, was in attendance.