KEEPING Up with the Kardashians” starlet Kendall Jenner’s football hunk boyfriend is hiding a heartbreaking suicide secret!

On Aug. 11, 2008 – when Kend­all’s beau Julian Brooks was just 15 – his dad Dexter shot himself to death at the age of 47. Now, Kendall, 17, lives in fear that the same tragic end could await her 19-year-old beau.

“Kendall is totally totally smitten with Julian, and she’s so terrified he might suffer the same fate that it keeps her up at night,” revealed a source.

The two young lovebirds spent the Fourth of July with Kendall’s family at dad Bruce Jenner’s Malibu bachelor pad, where he’s been staying since Kim Kardashian and baby North moved in with his wife Kris.

Meanwhile, Kendall and her little sister Kylie, 16, have been making waves with their wild summer partying at the ritzy beachside enclave.

“All hell has broken loose,” said a source. “Neighbors find teens passed out in the sand and the beach is littered with beer cans, empty wine coolers and remnants of marijuana joints.”

Still, August is said to be a tough time for Julian since it’s the anniversary of his dad’s death, and he continues to struggle with it. Adding to his problems, he was temporarily suspended from the University of Nevada-Reno football team this past summer for a “violation of team rules” before being reinstated.

And now Kardashian momager Kris Jenner apparently has worries about the romance.

“Kris is concerned because Julian’s dad committed suicide,” said another source. “She doesn’t know what kind of men­tal problems he had and whether they could be hereditary.”