There were aunts and uncles, parents and grandparents, plus plenty of potatoes and pie to go around. But at the Simpson family Thanksgiving celebration in Waco, Texas, on Nov. 24, there was one notable absence: Nick Lachey, whose split from wife Jessica had been announced just one day earlier. “We were sad he wasn’t there—we missed him,” Jessica’s uncle Gary Simpson told PEOPLE. “He is a good guy and we all liked him. We were sorry he wasn’t part of the group. There was an empty place.” Despite the still-raw breakup, his niece “is holding up fine,” he adds. “She’s going to be okay. I know it must be rough on her, but she’s doing good.” Surfacing three days after the Thanksgiving festivities, the newly single Simpson betrayed no hint of heartache. “She looked great,” says an observer at South Beach Tan, a tanning salon in Studio City, Calif., where Simpson—minus her wedding band—and a female pal showed up on Nov. 27. “One of the employees asked her how her Thanksgiving was, and she said, ‘It was beautiful.’ She was almost chipper.”

Perhaps she was simply steeling herself for the brewing storm. Almost immediately after Simpson, 25, and Lachey, 32, announced their split in a politely worded Nov. 23 statement—”This is the mutual decision of two people with an enormous amount of respect and admiration for each other”—friends of both stars began choosing sides, lobbing accusations in both directions. The two camps offer different explanations for what went wrong and when (see box). While Simpson’s camp says that she was fed up with her husband’s partying ways and his refusal to join her family in Texas for Thanksgiving, and that the pair decided to split after an argument the day before Thanksgiving, Lachey’s side tells a different story. One source close to Lachey says that following dinner with pals at an L.A. eatery on Nov. 22, Simpson blindsided her husband on the car ride home. “She said, ‘I don’t know if this is working. I want to file for divorce,’ ” says the source. “He was shocked. Nick was saying, ‘There are things we can do to work on this, and isn’t this worth fixing?’ And the answer was no.”

The next day, say several sources close to Lachey, Simpson asked if Lachey would still join her family in Texas. He refused, and the couple issued the statement confirming their split. “I know for a fact there wasn’t one event that brought it about,” says another source close to Lachey. “I think it was a general growing apart, as in most marriages. It’s very rare that it’s just one thing that causes people to break up. It’s usually over time a slow growing apart.”

In the ensuing days, the initial high tensions appeared to soften a bit. “They’ve spoken over the last few days,” says a source close to Simpson. “The fact that they’re talking is a good sign.” Still, as the impact of the split settled in, the couple whose young marriage launched them both into superstardom with the success of their MTV reality show Newlyweds: Nick and Jessica were left to grapple with their new, separate realities. “We love them both,” says Lachey’s mother, Cate Reinert. “It’s a difficult time.”

In fact, the last year has been a trying one for the pair, who spent much of their time away from each other—she was in Louisiana filming The Dukes of Hazzard, he was often in Sweden recording his upcoming album—and had to endure rumors of infidelity (emphatically denied by both). Then there was Simpson’s now-you-see-it, now-you-don’t wedding band and the couple’s third anniversary on Oct. 26, which they spent several continents apart, with Lachey in L.A. and Simpson doing charity work in Africa. Their last public outing as a couple, at a Nov. 16 party at Hollywood club LAX, also fueled talk of a split. “Justin [Timberlake] at one point was making fun of Jessica because she was sitting with her arms folded toward Nick, kind of scowling at him,” says an observer. “He was imitating her, like, ‘What’s up with that?’ ” And yet despite all the speculation, friends on both sides say that the official word of a breakup still came as a jolt. “It kept being reported as if they’d split, and they hadn’t,” says Jimmy Swan, a longtime friend of the Simpson family. “This really was new.”

Up until the announcement, the couple had not only steadfastly denied every new report of marital strife, but they continued to sound like, well, a couple of newlyweds on the subject of their marriage. Speaking to PEOPLE on his recent anniversary, Lachey seemed as smitten as ever. “I wrote [Jessica] a long letter and hid it in her suitcase and made sure she found it today,” he said. “You make the other person feel special because it’s easy to lose track.” He also noted that the couple’s recent getaway to Italy provided a much-needed respite: “It was nice to spend some time together.”

A source close to Simpson says that the Italy trip “reminded Jessica of what a wonderful relationship she had [with Nick] away from the press, away from her friends, away from his friends.” And yet this source says that any lingering vacation afterglow was killed within 24 hours of their return to L.A., when Lachey joined close pal A.J. DiScala, 34, himself newly separated from his actress wife, Jamie-Lynn Sigler, in Las Vegas. Combined with Lachey’s trip to Miami Nov. 18-21, where he hit hot spots Mynt and the Setai with DiScala, “it really upset her that she was at home by herself with the dog and he is with single guys partying,” says the Simpson source. “She wondered, ‘Do I have to follow you around to clubs to make you happy?’ She doesn’t like that world. Her idea of a great night is to order Chinese food and ice cream and watch movies.”

But those close to Lachey offer a nearly opposite version of events. They say that in fact Simpson had originally been scheduled to join her husband at appearances both in Miami and Vegas, and that he was honoring those prior commitments. Further, the other source close to Lachey says that it was her club-hopping, not his, that caused friction. “Nick is a little bit older than Jess, and he was ready to be more domesticated than Jessica is,” says the insider. “I think she still enjoyed the Hollywood lifestyle.”

When the pair met at the Hollywood Christmas Parade in 1998, Simpson was an 18-year-old popster deeply in the shadow of Britney Spears and Christina Aguilera, and Lachey was riding the boy band wave with his group 98°. Outspoken about her virginity, the Texas-bred Simpson—whose father is a former Baptist minister—instantly hit it off with the Ohio-reared Lachey, whom friends say is the more outgoing of the two.

And yet after their lavish 2002 wedding, Simpson emerged as the breakout star, parlaying her sweetly ditzy Newlyweds charm into a one-woman industry that currently encompasses fashion, beauty, movies and music. “I think Nick liked it much better when he was protecting Jessica and nurturing her,” says a source close to Simpson. Counters one source close to Lachey: “Every step of the way in her success, Nick was by her side. He wants nothing more than for her to succeed.”

Now it seems Simpson and Lachey will set out to succeed on their own separate terms. Both have upcoming solo albums as well as other projects in the works (see box). And yet even as they begin the tedious, painful process of disentangling their lives—Simpson has been staying at her parents’ house in L.A. while Lachey remains at the couple’s Calabasas, Calif., home—those who know them do not rule out a reconciliation. “Nick very much loves his wife,” says a source close to Lachey, “and doesn’t want to get divorced.”

Michelle Tauber and Ericka Sóuter. K.C. Baker, Joanne Fowler, Mark Dagostino and Tiffany McGee in New York City, Darla Atlas in Waco, Alicia Dennis in Austin, Lisa Ingrassia and Julie Jordan in Los Angeles and Nicole Weisensee Egan in Dover, Pa.