Khloe Kardashian's loved ones aren't entirely thrilled by her romance with rapper French Montana -- find out why in the new issue of Us Weekly

French Montana "ain't worried about nothin'," but Khloe Kardashian's family is. The "Cocaine Mafia" rapper and the reality superstar, both 29, have been virtually inseparable in recent weeks, with the brief exception of Kim Kardashian and Kanye West's wedding, and while Khloe herself seems thrilled with the romance, her loved ones suspect that Montana's intentions may not be entirely pure, a source reveals in the new issue of Us Weekly.

Sister Kim, 33, and stepdad Bruce Jenner, 64, are particularly wary of the Moroccan-born hip hop star. "[They] are very skeptical of him," a pal tells Us. "They think he's using Khloe for fame." See recent pics of Khloe out and about here.

They may not be wrong. A Montana source says he's eager to "sit at the cool kids' table" and "has been trying to get close to people he thinks are popular." Exhibits A and B? Jennifer Lopez and Miley Cyrus. (Montana raps on Lopez's "I Luh Ya Papi" and collaborated with Cyrus on the remix of his song "Ain't Worried About Nothin'.") "Being with Khloe means everyone knows who French is now," the insider adds, "so he's getting a lot out of it."

Which is not to say Khloe isn't. In the past two months, the Keeping Up With the Kardashians star has had a backstage pass to all of her beau's parties and performances, including Lopez's recent concert in the Bronx. As seen on her Instagram account, she even went on safari with him in Johannesburg, South Africa.

The relationship is Khloe's first full-fledged romance since she filed for divorce from estranged husband Lamar Odom last December. She and Odom, 34, were married for four years before they split amid revelations about his drug use and infidelity.

For more on Khloe's relationship with French Montana—including details on his checkered past, her preference for bad boys, and their wild sex life—pick up the new issue of Us Weekly, on stands Friday.