Police are appealing for witnesses.
It happened in The Strand at around 2.40am on Sunday 13 October.
It's reported a man assaulted a woman in her late teens, before pinning her partner to the floor and punching him in the face.
The suspect's described as having short, dark, cropped hair which was shaved at the sides.
He was wearing a dark shirt , dark jeans and black trainers.
Police Constable Steve Mingo, of Exmouth Police, said: “A large number of people were also waiting for taxis at that time and many intervened to break up the incident. I am looking for witnesses, and, in particular, looking to identify the suspect.”
Anyone who has information is urged to contact police by calling 101, or emailing email@example.com, quoting crime reference CR/092532/19.