Red Hot Chili Peppers' Guitarist -- John Frusciante Shredding Again ... This Time It's His Marriage

The "Blood Sugar Sex Magik" is dead for John Frusciante and his wife -- the former Red Hot Chili Peppers guitarist is getting divorced ... TMZ has learned.

Frusciante and Nicole had a decent run of nearly 4 years, before she filed the divorce docs in L.A. ... citing irreconcilable differences.

The couple didn't have any kids -- so child support won't be an issue -- but Nicole is asking for spousal support, and attorney's fees.

John, who's retained Laura Wasser as his attorney -- will have to give it away, give it away, give it away in the name game. Nicole wants to drop Frusciante, and go back to Turley ... her maiden name.

And now, a love song ...