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NICK & JESSICA
"He is a man of character and a man of honor," says Jessica Simpson, 24, of her husband of three years, Nick Lachey. When they first met in 1998, the sparks were immediate. "I couldn't stop looking at his mouth and wondering how great it would feel to have mine on his," she says. For his part, Lachey, 31, praises his wife's "deep, intellectual" qualities and her "physical beauty."
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JENNIFER & MARC
They split their time between homes in Miami, Manhattan, Los Angeles and Brookville, N.Y., but wherever they are, Jennifer Lopez, 35, and her crooner-actor husband Marc Anthony, 36, have their focus on each other. "Marc and Jennifer are in a relationship of mutual respect, love and support," says a friend of the newlyweds, who married in June. "They are an impressive couple to watch."
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BRITNEY & KEVIN
It's been a whirlwind year for Britney Spears, 23, and Kevin Federline, 27: After marrying in September, they're now expecting their first child together. But the quick pace suits Spears just fine. "I kissed a bunch of frogs and finally found my prince," says the pop star of her romance with the former backup dancer (who's an aspiring artist himself). "I feel like I've found my happily ever after."
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DEMI & ASHTON
"I love being with her. She makes me a better person," Ashton Kutcher, 27, says about Demi Moore, 42, his girlfriend of two years. "We work together on life every day." They share a devotion to Kabbalah – and to Moore's daughters, Rumer, 16, Scout, 13, and Tallulah, 11. And though they won't comment on it, buzz has been building that they soon could take their relationship to the altar.
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SEAL & HEIDI
When it came to asking for his sweetheart's hand in marriage, British singer Seal, 42, spared no expense, proposing to model Heidi Klum, 31, at 14,000 feet in Whistler, B.C., on a glacier "in an igloo built just for the moment," he explains. The couple, who began dating last year, are already a family: Seal calls Klum's 11-month-old Leni (with ex Flavio Briatore) "my daughter" and they're expecting their first baby together in the fall.
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FAITH & TIM
"She's perfect as far as I'm concerned," says country star Tim McGraw of his wife of eight years, Faith Hill. So, what's the secret to their long marriage? "I'm a man that lives in a house with four women," says McGraw, 37. "So probably the secret is to shut up." And Hill, 37, says her handsome husband – and father of Gracie, 7, Maggie, 6, and Audrey, 3 – is "my brick. He's my wall."
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PENELOPE & MATTHEW
Their romance on the Morocco set of Sahara last year has blossomed into a full-fledged relationship. "It's not hard to find something to be attracted to," says Matthew McConaughey, 35, of Spanish beauty Penelope Cruz. Meanwhile, Cruz, 30, fell in love with her beau's easy way. "He is someone who listens." Even Cruz's pal Salma Hayek acknowledges the pair's compatibility, saying, "They are very happy with each other."
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JUDE & SIENNA
It's not hard to see why Sienna Miller said she's the "happiest girl alive" after getting engaged to PEOPLE's Sexiest Man Alive, Jude Law, 32. The actress, 23, has said of her fiancé, "Sometimes I can't believe how handsome he is." But their relationship, which began on the set of Alfie, is more than just a mutual admiration society. Miller is also close to Law's three kids, Rafferty, 8, Iris, 4, and Rudy, 2 (with ex-wife Sadie Frost).
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CAMERON & JUSTIN
Two years after meeting at the Nickelodeon Kids Choice Awards, Cameron Diaz, 32, and Justin Timberlake, 24, are still living it up together. And despite rumors that they're next to join the list of engaged celebs, their reps insist wedding bells aren't soon to ring. But there's one sign that things could take a serious turn: They were spotted checking out a $13 million Pacific Palisades estate.
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WILL & JADA
He played a dating coach in Hitch, and in real life Will Smith says he's an expert in romancing his wife of seven years, Jada Pinkett Smith: He even surprised her one birthday by flying her to a San Francisco restaurant she'd been eyeing. But most important, says Smith, 36, "I step up when she needs me to step up, and back up when she's got it." Says Pinkett Smith, 33: "We're best friends."
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REESE & RYAN
"It was a pretty intense, emotional connection," Ryan Phillippe, 30, has said of meeting Reese Witherspoon at her 21st birthday party in 1997. And what does Phillippe find appealing of his wife of almost five years? "Reese is a happy, lighthearted person, but she's also incredibly intelligent." Witherspoon, 29, who's balanced a successful acting career with raising kids Ava, 5, and Deacon, 1, says that she sees herself as "a mom and wife, and that's what I like to be."
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LEO & GISELE
During their five-year relationship, Leonardo DiCaprio, 30, and Gisele Bundchen, 24, have endured their share of ups and downs (including a temporary breakup in 2002). But the supermodel and the Oscar-nominated actor – whom she calls "a wonderful person with a big heart" – always end up back together. "He's still the best to me," Bundchen says.