The man was booked into the Skagit County Jail for investigation of second-degree murder.
The sheriff’s office said it received a call Sunday morning from one of the man’s neighbors who said the suspect had told him that he had just killed his wife.
Deputies found the suspect standing outside of the house and took him into custody without incident.
Medical staff attempted to revive the man’s 61-year-old girlfriend, but couldn’t. The sheriff’s office said the woman had suffered “multiple injuries to her head and face.”