12/04/2008 AT 05:15 PM EST
Marriage for Beyoncé and Jay-Z can be a "power struggle," according to the singer – especially when both superstars have their own careers and millions of dollars.
"If I didn't respect someone and they didn't have that strength, then I would be bored," the 27-year-old tells Elle
in its December issue. "I wouldn't be attracted to them."
The couple, who secretly wed
in April, topped Forbes
' list of richest couples this year with an estimated worth of $162 million.
As for starting a family with Jay-Z, 39, Knowles told
Ellen DeGeneres she definitely wants to have "a couple" of children – but not for a while.
"I'm terrified of having a child," the Cadillac Records
actress reveals in Elle
. "No way! I'm terrified of delivering a child because I saw my nephew being born. That traumatized me. I'm only 27. I've got time."
Get the scoop on Beyoncé & Jay-Z's secret wedding