With the sleepless nights, dirty diapers and high emotions that accompany young parenthood, perhaps the big blowup was inevitable. On Nov. 30 Britney Spears and her husband, Kevin Federline, had such a heated argument that, a source close to the couple says, Spears dropped the D-word, and Federline bolted from their Malibu home. "She wanted a divorce," says a friend of Spears's. And, says a source close to Federline, "when she's upset with him, he likes to give her some space. I don't think she's upset with him because of something specific he's done. I think she's overwhelmed with her new lifestyle—being a wife and mother—and sometimes takes it out on the people who she's closest to and who she knows will stick around." Spears's way of taking it out on her husband? By showing up that night at the L.A. club LAX and dancing into the wee hours with friends. "It was definitely a girls' night out," says an LAX partner. "Kevin was being punished."

Of course, Federline, 27, didn't seem too tortured during his own marathon of clubbing in Vegas a few days later: First he and his all-male entourage hit Pure Nightclub, where he caught up with Nicole Richie's fiancé, DJ AM, then partied at the club Tao Las Vegas until 4 a.m. In any case, the punishment proved short-lived. After her 24th birthday on Dec. 2, Spears took a quick jaunt to Vegas (where she checked into the Wynn Las Vegas resort, half a mile down the Strip from her husband's suite at the Venetian), then repaired to Louisiana to spend time with her mother, Lynne, and sister Jamie Lynn. But by Tuesday, according to a source close to the couple, she had settled back into her Malibu mansion with her husband and their 3-month-old son Sean Preston. "This has happened before," says an insider. "They always work it out."

And thus goes the marry-go-round for the Federlines. While they've had their fair share of tiffs since their 2004 nuptials, a source close to the couple says this fight was the worst yet. And friends from both sides say the two share the blame for their recent strife. Says a source close to Spears: "Kevin can be dismissive of her, but Britney's all over the place emotionally."

Part of her anger, sources say, is her feeling that Federline is more fond of going out to a bumping club than staying home with a burping baby. But his friends scoff at the idea. If anything, says a Federline source, he's "more caring" since Spears gave birth to Sean Preston in September. "All of that is overblown," says the source. "He's only gone out a handful of times. He's tried so hard to help [Britney] after she had the baby."

And now they're each putting in the extra effort to mend their relationship. "Kevin loves her," says a Federline source. "He wants to make their marriage work." But will it? "Britney really loves him," says a source close to Spears. "They're back together." But as for their future, adds the source, "who knows?"

Michelle Tan and Rennie Dyball. Michael Fleeman and Lycia Naff in Las Vegas, Marisa Laudadio, Alexis Chiu and Kimberly Lansing in Los Angeles and Ruth Laney in Kentwood, La.

  • Contributors:
  • Michael Fleeman,
  • Lycia Naff,
  • Marisa Laudadio,
  • Alexis Chiu,
  • Kimberly Lansing,
  • Ruth Laney.