Ashton Kutcher and Demi Moore's May-December romance initially sent shock waves through Hollywood in 2005. And the duo managed to shock again when they later married.
There may be a 15-year age gap between the pair, but Kutcher quickly found his place in the Moore-Willis family. Not only has he become close with Moore's three teenage daughters, Rumer, Scout and Tallulah, who affectionately call him M.O.D. (for "My Other Dad"), he also has become friends with Moore's ex-husband, Bruce Willis. The brood can often be seen palling around at events from the Super Bowl to Hollywood premieres. Kutcher and Moore even take vacations with Willis.
In a strange blending of the past and present, befriending the ex and his or her new love appears to be a growing trend among celebrities who swap partners more often than movie roles.
Kimora Lee Simmons is dating Oscar nominee Djimon Hounsou, and Russell Simmons, her ex, is supportive of the relationship.
Tom Cruise's ex, Spanish actress Penelope Cruz, attended his Italian wedding with Katie Holmes and was one of the first people to see baby Suri.
"As more people split in Hollywood, you will see more cases of this happening. It's a small community and it works best when exes get along, especially when children are involved," Dina Sansing, West Coast deputy editor of Us Weekly magazine, told ABC News' "Good Morning America."
Making the Kids Priority No. 1
So what's the secret to amiability between new couples and their former lovers?
When ABC News' "Good Morning America" asked Willis how he gets along so well with Kutcher, he said: "I try not to judge. It could be a lot worse, you know? He's smart and he gets the Good Housekeeping seal of approval. You have no choice who you fall in love with, and I think they make a great couple."
Sansing said the threesome makes for a good example.
"Demi, Ashton and Bruce are one of the great examples of an extended family in Hollywood. They all get along very well. It stems from Demi and Bruce having a good relationship after their split. Ashton has been welcomed into the family. He has struck a good balance of being a father figure to the children, without overshadowing Bruce. It's a great dynamic," she said.
Moore told ABC News' "Good Morning America" that one of the reasons her divorce is better than some people's marriages is that she put her kids' needs first.
"My intention came truly out of my desire to place my children as the priority, and what you have as a couple -- those were your issues, not your children's. I think, perhaps, having been the product of divorce, where I felt a little bit like the pawn," she said.
Will and Jada, and Ex Sheree Makes Three
Will Smith and Jada Pinkett Smith have also made their children top priority. Smith's ex-wife, Sheree, was the first to see his then-newborn baby with Jada. Sheree and her son with Smith, Trey, were visiting a sick grandmother at Cedars-Sinai when Jada gave birth in 2000. The two women are said to be good friends, keeping it all in the family. Will and Jada even worked on a sitcom about an ex-wife, a man and a new wife trying to get along for the sake of a wonderful little boy.
"Many ex-spouses are in conflict, and this undermines their children's emotional health and happiness. It is great to have celeb exes as role models who put aside their differences in order to come together and provide solid parenting for their children," said psychologist and relationship expert Diana Kirschner, author of "Love in 90 Days Boot Camp."
Russell and Kimora Simmons wed in 1998 and have two young daughters, Ming Lee and Aoki Lee. They split last year but remain friends and continue to work on their clothing businesses, Phat Farm and Baby Phat.
People magazine recently asked Simmons about his estranged wife's relationship with actor Djimon Hounsou.
"I don't know what they're doing, but he's a nice guy. She'd better be happy. He's one of the sweetest guys in the world," he said.
Simmons also told People, "We have our businesses together and our children, and we do everything for our children, no matter what."
The tough schedules and travel that actors must often contend with make celebrity romances difficult. Kirschner said couples who break must really focus to remain good parents after a divorce.
"Initial infatuation dies out, and this means that over time romance always has to be rekindled in a relationship. Many couples start out being in love with each other but then contend with too much time spent apart or other conflicts that stop them from nurturing that love and romance. If they still mesh well as a parental team, as friends and/or as business partners, they may hold on to those aspects of their relationship," Kirschner said.
More kind words came from Penelope Cruz about TomKat and their new baby Suri, less than three years after she and Cruise called it quits.
"I met Suri," said Cruz. "She is really beautiful. She is really special. One of the most beautiful babies I have ever seen. And I am extremely happy for them. They are really happy and doing great." Cruz even posed with Katie Holmes at an Armani pre-Oscar event this year.
So what does the real world think of these exes befriending exes?
"If you're with someone for a long time, even if you break up, they become like family. No matter what, you want your family with you. Of course, even in a family situation, if your brother or sister is a jerk, you don't want them around. But I can totally understand why exes would remain friends," said Bettina Hill of Baltimore.
Myrna Taylor, also of Baltimore, isn't so sure about staying too close with the ex. "I don't think I'd want my ex at my wedding, that would be weird. But we have kids together and he's welcome at their parties and events. We'll always have the kids in common," she said.
And Meghann Gibbons of Tampa told ABC News' "Good Morning America": "Who knows if it's really done for true friendship or just for image and public perception. One would hope, though, that it's a good example of a mature relationship, and I would love for more people who aren't celebrities to be happy and not so nasty to their exes and to have harmonious grown-up relationships."
Sansing agreed and said: "It's very good for a celebrity's public image to get along with their exes and that person's new love. People are impressed when the situation is amicable. It's nice when they can set a good example for the rest of the world."