He said it was coming ... and now Lane Kiffin's wife has made it official -- filing divorce papers in Los Angeles ... TMZ Sports has learned.
Layla Kiffin -- who married the Alabama offensive coordinator back in July 2000 -- pulled the trigger on March 4th ... citing irreconcilable differences.
The couple has 3 minor kids together -- and she's asking the court for joint legal custody. However, she wants primary physical custody with Lane getting visitation.
We're guessing the proposed arrangement has to do with Lane's busy traveling schedule.