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Scott Disick & Sofia Richie Are 'Serious,' Source Says: 'Nobody Notices the Age Difference'

Aurelie Corinthios

Scott Disick and Sofia Richie are going strong.

Despite the pairing initially raising eyebrows, a source tells PEOPLE that Disick, 34, and Richie, 19, are “very serious.”

According to the source, Richie has been a positive influence on Disick, who is known for his late nights out and has openly struggled with alcohol abuse.

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

“They’ve been traveling together to Mexico, New York and Venice and just hanging out,” the source adds. “His friends adore her and nobody notices the age difference. She is very mature, she grew up in Hollywood and has always been in older situations. They seem really happy.”

Sofia Richie and Scott Disick in Venice

The couple first sparked romance speculation in May after they were pictured cuddling up aboard a yacht in the south of France during the Cannes Film Festival. At the time, Richie — who previously dated Justin Bieber — adamantly denied anything romantic was going on, tweeting that the two were “just homies.”

By mid-September, a source told PEOPLE they had become “inseparable,” and they confirmed their romance via social media later that month, packing on the PDA during a trip to Mexico.

Scott Disick and Sofia Richie in Mexico

While a source previously told PEOPLE that Richie’s famous father Lionel isn’t too pleased about the relationship — “Lionel knows Scott’s playboy ways, and he doesn’t want to see his daughter get hurt,” the insider said — the model has insisted that her dad is on board.

“He’s good — he’s been very nice,” she told E! News at the SAG-AFTRA Foundation Patron of the Artists Awards in Beverly Hills earlier this month.

“He’s been very cool,” she added. “He’s very supportive, whatever that means,” she added as Lionel, 68, jokingly pointed a gun-shaped hand gesture at his head.

“I am into her business and she’s trying to keep me out of her business,” he said.