They seemed to be a happy family in the making. In June 2000, as '70s supermodel Cheryl Tiegs and Rod Stryker, her yoga-teacher husband, awaited the arrival of twins Jaden and Theo, she told PEOPLE: "I don't have to prove anything anymore. I can concentrate on my family now." Added Stryker: "We're embarking on an amazing adventure."

Sixteen months later, the adventure appears to be over. On Oct. 8 Stryker, 44, filed for divorce from Tiegs, 54, citing irreconcilable differences. He asked Los Angeles Superior Court for custody of the boys. "His concerns," says Peggy Garrity, Stryker's attorney, "are solely focused on those little babies." Tiegs and her attorney had no comment on Stryker's petition.

The boys, now 15 months old, who were conceived after one of Tiegs's eggs (fertilized in vitro by Stryker) was implanted in a never-identified surrogate mother, seemed to be at the center of her new life. Divorced since 1995 from actor Tony Peck, Gregory's son, Tiegs, with previous marriages to director Stan Dragoti and photographer Peter Beard, met Stryker in 1997 while taking a class at his Los Angeles studio. They wed the following year. Tiegs already had Zack, now 10, from her marriage to Peck, but Stryker, never married before, wanted desperately to be a dad. "The way I was being a stepfather," he told PEOPLE, "assured her that I was going to be a great father."

Now that the union is foundering, a close associate of Stryker and Tiegs—who occupy separate areas of their Bel Air house—says, "Honestly, I wasn't surprised. She's a great mom to Zack. And she loves her babies. But I think she agreed to the surrogacy because of Rod. I think she thought she was done with having children."

This week's cover

On Newsstands Now!

Saved by the Bell Reunion

The hookups, the meltdowns, the memoires

The case reveals what was really going on what they think of each other now!

Get 4 FREE PREVIEW Issues! Click here now