The two have been linked since September of last year

By Jessica Fecteau
January 14, 2018 03:03 PM

Scott Disick and Sofia Richie‘s romance continues to heat up.

The reality star, 34 — who has been dating the 19-year-old since last September — posted a photo on Instagram, Saturday, of the model dressed in a black bikini and sunglasses, posing on a rocky shoreline.

Credit: Scott Disick/Instagram

“Water,” Disick captioned the shot of Richie, with the ocean visible in the background.

The couple, who recently celebrated their first Christmas and New Year’s Eve together, were also spotted having a casual date night at Italian hot spot Toscana in Los Angeles last Wednesday.

Credit: BackGrid

A source told PEOPLE in November they are “very serious” and that the daughter of Lionel Richie has been a positive influence on Disick, who is a father of three with ex Kourtney Kardashian, and has openly struggled with alcohol abuse.

“She’s been great for him,” the source said. “She’s made a big impact on his life and hasn’t partied at all since they met.”