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.
Layla is also asking for spousal support -- but notes the two are engaged in mediation to resolve other undisclosed issues.
Lane issued a statement about the split back in February saying the decision to break up was mutual -- adding, "We will maintain an amicable relationship with respect for each other as we raise these three wonderful children."