How Gwen Stefani and Gavin Rossdale have survived some unusual marital bumps remains a mystery to the singer.

“I don’t know. It’s one of those mad love affairs that you can’t live with and you can’t live without, and you just keep going and going,” Stefani, 37, tells Britain’s The Observer about her 5-year marriage to the Bush frontman-guitarist.

“And time goes by and you get the rocky times and the intense love times, and then you get the reward of having the baby,” she says, referring to son Kingston, born in May 2006.

“It’s just this ongoing saga,” she adds. “I’m interested to see what’s going to happen next, you know?”

Among one of the bigger surprises along the way: the revelation that Rossdale is the father of teen model Daisy Lowe, a fact revealed in 2004 – two years after he and Stefani tied the knot.

Lowe is the daughter of singer Pearl Lowe, a Kate Moss pal with whom Rossdale had a brief affair, says the newspaper.

Currently, Stefani is on tour in Australia – accompanied by Kingston, whom she is still nursing.

“I don’t know when I’m going to stop breast-feeding,” says the working mom. “I’ll just keep going while I can – like, he’s getting his teeth so it is a little bit scary. He’s bitten me a few times!”