Russell & Kimora Lee Simmons' Daughter Splits with A lot Older Boyfriend

Aoki Lee Simmons has already called it quits with her much older boyfriend … TMZ has confirmed.

The exact reason for their split remains unclear — but we’re told Aoki isn’t planning on dating restaurateur Vittorio Assaf beyond the time they’ve already spent together in St. Barts … where they’ve been canoodling for the past several days.

While we know Russell was supportive of the relationship — People Mag reports that Aoki’s mom was not approving at all … in fact, they say KLS was “concerned” about the age gap.

Aoki herself also seemed to scoff at the haters in some since-deleted social posts — where she was referring to Vittorio with pet names — but in the end … this ain’t going anywhere.

Just as fast as the news came, it’s fizzled out — remember, it was just last week when news broke Aoki was hooking up with Vittorio after PDA-packed vacation photos of them from St. Barts emerged.