Brad Pitt & Angelina Jolie "together and very happy,"

Kosinski, comes of the heels of Star Magazine's Brad Pitt and Angelina Jolie breakup story.

Sources tell Star that Brad Pitt and Angelina Jolie are cracking under the strain in their three-year relationship and they'll view their upcoming time apart as a trial separation of sorts.

Angelina, 31, is heading off to Prague to work on her new action thriller, Wanted, while Brad, 43, is staying behind in L.A. "This is going to be a trial separation for them," a source tells Star. "They have so many serious issues between them, that giving each other this space might allow them to step back, think about what they mean to each other and decide where they want to go in the future."

"Brad is forcing himself to go with the flow, but he must be very frustrated," reports a source. "He can't keep up with Angelina, who keeps changing things around.

"They'll sit down and agree on things, but then she'll just do something else! Like taking on this film just a few weeks after adopting her new Vietnamese son, Pax. She promised that she was going to be a stay-at-home mother, and then she changed it up."

"This really is a test for them," a friend tells Star.

Pitt's publicist, Cindy Guagenti, tells Us, "I responded to those two tabloids [Star Magazine and Life&Style Weekly] with the correct information and they choose not to run it. There is absolutely no trial separation." Guagenti continues, "As a matter of fact, Brad and the kids are traveling to Prague to be with Angelina while she films her movie. Then they are both going to Cannes to promote Oceans 13 and A Mighty Heart. After that, the whole family is going to Los Angeles for the premiere of Oceans 13 and then to New York for the premiere of a Mighty Heart."

Earlier this week, The Daily Mail ran a story titled Is it the End of Brad and Angelina? The article alleged that “the passion between Brad and Angelina has cooled in the past year and she's very close to breaking up with him.�

“They're bickering an awful lot these days. They're like an old married couple with kids -- and they never even got married."