Shooting their movie "Scream 4" this summer, things didn't seem right between David Arquette and Courteney Cox. The pair put on a united front for daughter Coco, 6, but often retreated to separate trailers between takes.

"It seemed like the worst-kept secret that things were weird between them," a set source tells PEOPLE in this week's cover story.

In the wake of their separation announcement this week -- and Arquette's recent revelations about the couple's issues and their sex life to Howard Stern -- friends of the famously mismatched pair say they always had differences but seemed to work through them.

Now, however, both Arquette, 39, and Cox, 46, are figuring out where to go from here.

"This was not an overnight thing," a source close to the pair says of their trial separation. "They needed to figure things out and try to find a happy place again."

Christina Aguilera has split with husband Jordan Bratman, but there was no immediate talk of divorce, her representative said Tuesday.

"Although Jordan and I are separated, our commitment to our son Max remains as strong as ever," Aguilera said in a statement released Tuesday through her representative.

The 29-year-old singer-actress and the 33-year-old music executive married five years ago. Their son, Max, was born two years ago.

Aguilera co-stars with Cher in "Burlesque," a major feature film set for a Thanksgiving release.

Musician Ben Harper filed for divorce from actress Laura Dern after five years of marriage, citing irreconcilable differences and seeking joint custody of their two children, PEOPLE confirms.

The papers, filed Friday, claim the pair separated in January, TMZ reports.

Dern, 43, and Harper, 40, were married in 2005 in Los Angeles. They have a 9-year-old son and a 5-year-old daughter.