Prosecutors say 42-year-old Jennifer Colwell pleaded not guilty on Wednesday to felony arson.
Orange County sheriff's spokesman Jim Amormino says Colwell was apparently distraught over the failed relationship.
KCBS-TV says the breakup led Colwell to stuff a pillowcase with gifts her ex bought at Intimate Obsessions.
Investigators say she then went to the Dana Point store early Tuesday, soaked the pillowcase in gasoline and set it on fire in an attempt to burn down the business.
Firefighters extinguished the blaze before it spread to the lingerie store.