WARREN BEATTY and ANNETTE BENING marriage is falling apart at the seams – and friends fear the Hollywood power couple could be on the fast track to a $108 million divorce!

Insiders say the simmering tension over their transgender son Stephen’s lifestyle has finally reached the boiling point, and the two haven’t been seen photographed together in public for at least six months. Stephen, 21, was born a female and named “Kathlyn.” 

He began his transformation into becoming a man in 2010 and now takes hormones to sound and look more masculine, says a source.

While Mom Annette, 55, has fully embraced his new identity, her 76-year-old husband has had a “very difficult time coming to terms with it,” the source continued.

“Warren doesn’t understand the whole transgender thing at all, and it’s driven a deep wedge in his marriage.

“Although Annette and Warren still love each other, pals believe that the next step could be divorce court.”

The latest problem for Warren, say insiders, was a public service announcement that Stephen made. In it, he protests a New York State Medicaid regulation that excludes transgender people from getting healthcare coverage.

In addition to becoming an outspoken advocate for the transgender community, the college student also revealed on Twitter that he has a boyfriend, blithely noting: “I’m trans and gay. Double the fun.”

That kind of behavior apparently doesn’t sit well with his dad.

“Warren’s an intensely private person and he’d rather that Stephen keep his sexual- ity more low-key,” explained the source. Another insider added: “Stephen’s activism has deeply affected Annette and Warren’s marriage.

They don’t communicate much and don’t seem to want to be in each other’s lives anymore.

“No one is cheating with anyone else – they’ve just drifted apart.”