During an appearance on Bravo TV's The Daily Dish podcast, KUWTK executive producer Farnaz Farjam said the supermodel had a "rule" about her boyfriends appearing on the E! series, which aired its final episode last week. (The two-part reunion begins Thursday.)
"Kendall's always had this rule - she felt like she had to be with someone for at least a year before she let them be a part of the show, because she doesn't always know what people's intentions are," Farjam said. "So that's why we kind of kept her personal life out of it, just because she had a rule."
Indeed, fans never did get to see any of Kendall's relationships unfold on screen, and her sister Kylie Jenner, 23, took her own step back from the show in recent years.
"I feel like Kylie became more participatory this last season towards the end, and Kendall has dipped in and out," Farjam said. "But they were at an age ... like, if you think about when you're a young adult coming into adulthood, I think you sometimes care a lot more what the outside world has to say about you."
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Kendall, who is notoriously private about her dating life, has previously been linked to Harry Styles, Philadelphia 76ers guard Ben Simmons and Brooklyn Nets forward Blake Griffin. She's currently dating Phoenix Suns player Devin Booker, with whom she made her relationship Instagram official on Valentine's Day this year.
Kendall and Booker, 24, celebrated their one-year anniversary on Sunday, each posting sweet photos together on Instagram.
Kendall Jenner/Instagram Kendall Jenner and Devin Booker
"This is the happiest Kendall has ever been in a relationship," a source told PEOPLE in April. "She and Devin started out slowly, but have dated for about a year now."
And while Kendall has remained "very private about their relationship," the insider said it was "obvious that they have something special going on."
Part one of the KUWTK reunion, hosted by Andy Cohen, airs Thursday at 8 p.m. ET on E!