They were alerted by a taxi driver who left the pair home.
When they arrived, the woman flagged police down, saying the man had chased her with a shovel.
PSNI Foyle took to social media to thank the taxi driver.
They said they 'dread to think' what may have happened if they weren't there.
He is due to appear in court in connection with the incident.
Northern Ireland’s record-breaking Olympians to be celebrated at Belfast event
By Rebecca Black (PA)
Consuming berries, tea and red wine ‘may reduce the risk of dementia’
By Rebecca Black (PA)
Harland and Wolff parent company to enter administration
By PA Reporters
Man appears in court charged with murder of mother
By Jonathan McCambridge, PA
Fire at derelict hotel ‘believed to have been started deliberately’
By Jonathan McCambridge (PA)
Download the Q Radio app to keep listening, wherever you are! It's available on Apple and Android devices.
Download from the App Store Download from Google Play
