Aoki Lee Simmons, 21, kisses Serafina co-founder Vittorio Assaf, 65, on romantic trip to St. Barts (photos)

Despite a 43-year age difference, model Aoki Lee Simmons and her man are going strong as can be seen in photos from their vacation.

Aoki Lee Simmons, 21, was spotted kissing restaurateur Vittorio Assaf, 65, during a romantic vacation to St. Barts.

In photos obtained by Page Six exclusively, the youngest daughter of Kimora Lee Simmons and Russell Simmons packed on the PDA with the much-older Serafina co-founder while enjoying time at a beach.

At one point, Aoki, a Harvard graduate, posed for Assaf as he took pictures of her with his phone. They also took a dip in the clear blue water and shared a steamy kiss while on the white sand.

They also took a dip in the clear blue water.

See photos below.