"When I was younger, I used to be the cheater," the Black Eyed Peas singer, 35, tells Elle in its May issue, on newsstands April 14. "I'm not talking about going all the way – I wasn't doing that in high school!"
She explains: "I'd have boyfriends and then spring break would come around and I'd be a little bit naughty."
But the performer's relationship style has, of course, completely changed, especially since marrying Josh Duhamel in January 2009. "I'm a relationship girl, a romantic," she says.
"You grow a deeper love for each other, besides the initial lust and falling in love and all of that," she adds about their marriage, which was rocked in November after a stripper claimed she had an affair with Duhamel. The couple denied the allegations.
"You come to know each other a lot better, you grow together," she says, "and it makes you love each other that much deeper."