Jermaine Dupri backs up his boo, Janet Jackson

If you set out to make a definitive ’80s or ’90s pop CD and it didn’t include Janet Jackson’s trademark wisp, your disc would be nothing more than a shiny coaster. With 26 million albums sold in the United States and a record seven top 5 singles from one CD (Rhythm Nation 1814), Ms. Jackson is downright nasty.

But over time, fans have gone from singing “Let’s Wait Awhile” to saying it’s been a while since the last hit. And truthfully, it’s got Jermaine Dupri’s stomach in a knot.

“That’s why this industry is so fucked up,” says Dupri, Jackson’s longtime love interest who also contributed production to her last three albums. Discipline, Jackson’s 10th studio release, sold a paltry 415,000 copies in the United States since its February ‘07 release. As a result, Jackson parted with Island Def Jam last week, blaming lackluster sales on the label’s failure to promote.

“With the older artists, it matters if you got record sales. With the younger artists, it doesn’t matter what their record sales are; it’s more about how many times y’all see them,” says Dupri, who also heads up Island Def Jam’s urban division. “I had this conversation with Usher. Right now, people think that Chris Brown is a bigger star than Usher. Usher sold 10 million records before this last album. I don’t understand how we keep switching from record sales to perception.”

Still, the 42-year-old icon has positioned six albums atop the Billboard charts – a feat only accomplished by three other women: Mariah Carey, Madonna and Barbara Streisand. “If you’re talking about career sales,” Dupri says, “none of the young girls are anywhere close to her.”

It marks the second time in two years that Jackson has left a label on bad terms. Jackson followed Dupri to Island Def Jam after both fled Virgin Records in July 2007 in the wake of disappointing sales of Damita Jo (2004) and 20 Y.O. (2006).

But Dupri still stands by his woman. And onstage, at least, Jackson remains in total control. “It’s like a Vegas show to me,” Dupri says, hyping her well-received Rock Witchu Tour. “It’s almost too much for just going to an arena, personally.”