AceShowbiz - The Kardashian/Jenner clan apparently has had enough of Kourtney Kardashian dating a much younger guy. Amid rumors of her romancing 20-year-old Luka Sabbat, her famous sisters reportedly don't approve of their relationship, and the fact that the alleged couple has a huge age gap "totally" creeps them out.

A source close to the family tells Radar Online that Khloe Kardashian asks her older sister to "grow the f**k up" because the latter declares that she "will never date anyone older than half her age." Kim Kardashian allegedly supports Khloe as she thinks Kourtney "is just starving for attention and cannot believe that she would go for Luka."

Kendall and Kylie Jenner are reportedly also bothered by the fact that she's dating Luka considering that the young model, who was recently added to "grown-ish" season 2 cast, is younger than both of them. But Kourtney pays no mind to them because she "thinks that it makes her hotter."

As for Scott Disick, he believes the oldest Kardashian sister only dates Luka to rival his relationship with Sofia Richie. "Scott is convinced that she is trying to one up him with a 20-year-old," the so-called insider shares. "No one approves of this barely legal cling-on."

Kourtney was first reportedly linked to Luka when they were spotted enjoying a dinner date at The Nice Guy restaurant in Los Angeles last week. The mother of three wore a sparkly white mini dress for the dinner date, while her rumored love interest rocked a black T-shirt and sneakers.

A source said to E! News that the pair chatted for hours during the outing. "They seemed to be really bonding and having fun," the insider noted. "They say in the back trying to keep a low profile, and then a few friends arrived to meet up with them. Kourtney was smiling a lot and sitting next to Luka the entire time."