26-year-old Fonseca -- who played Katie Deauxma in the movie -- filed the docs in L.A. County Superior Court against hubby Matthew Smiley, citing "irreconcilable differences."
They were married in April 2009 and split in July 2012. They have no minor children.
According to the docs, Lyndsy wants to block the court from awarding Matthew spousal support.
Now here's a video of Lyndsy eating an ice cream cone.