Ben Foster Divorcing Laura Prepon After 6 Years of Marriage

Ben Foster is calling it quits on his marriage to Laura Prepon ... and we're told the estranged spouses are already living separately.

In the divorce docs obtained by TMZ ... Ben cited "irreconcilable differences" as the reason behind his split with Laura -- and asked the court to enforce their prenuptial agreement from 2018. He noted September 9 as their date of separation.

This coincides with what sources tell us ... as they say the "Orange Is the New Black" actress and the 'X-Men' actor broke up sometime in the last few months, and that Laura is currently living in Tennessee while Ben resides in Los Angeles.

There doesn't seem to be a reconciliation in Laura and Ben's future either ... as our sources say the "That '70s Show" alum has ditched her wedding ring.

Laura and Ben first met when they were just teenagers, sharing Danny Masterson as a mutual friend for many years.

The duo's relationship turned romantic in 2016, and Laura and Ben welcomed their first child, a daughter, in August of the next year.

The pair then tied the knot in June 2018 ... going on to also have a son in February 2020.