Domestic violence: Emma Roberts, shown with Evan Peters in May in Los Angeles, was arrested on July 7 in Canada for domestic violence
Roberts was released hours after her arrest because Peters declined to press charges, according to TMZ's report.
The two were said to be hitting each other and Roberts was arrested because Peters had obvious physical injuries, a source told the website. A law enforcement source said Peters also had a bite mark, but a source close to Roberts denied the Valentine's Day actress bit him.
The couple are now reportedly back together and are working on Peters' hit show American Horror Story.
Passionate affair: Roberts and Peters shared a kiss in May while in line at the Metropolitan Museum of Art in New York City
The Scream 4 star and Peters met last year on the set of Adult World and have been spotted in public displays of affection since becoming a couple.
The two attended a Halloween party in Beverly Hills last October and were holding hands as Roberts was dressed in the same iconic outfit her famous aunt wore in the opening scenes of 1990's Pretty Woman.
They also joined other celebrities in April at the Coachella Valley Music and Arts Festival in Indio.
In May, they kissed while waiting in line to buy tickets at the Metropolitan Museum of Art in New York City.
Hotel argument: Emma, shown getting fast-food on Sunday in Los Angeles, was freed after her boyfriend refused to press domestic violence charges
Peters has called the Nancy Drew star 'the love of my life' and stars in FX's hit horror show while his girlfriend has a recurring role.
MailOnline has reached out to Roberts and Peters's representatives for a comment and are yet to get a response.
Emma is the daughter of Eric Roberts, an actor best known for his work in 1985's Runaway Train and his troubles with drug abuse.
Famous family: Emma and her aunt Julia Roberts are shown together in April 2012 at a movie premiere in Los Angeles
He was arrested in 1987 for possession of cocaine and marijuana and in 2011 appeared in Celebrity Rehab for his dependency on medical marijuana.
He was estranged for years from his famous sister Julia but they have since reconciled.
Emma will next be seen in We're the Millers - due out August 7 - alongside Jennifer Aniston, Jason Sudeikis, and Ed Helms.
In the dark comedy Emma plays Julia, a 'disturbed 20-year-old runaway' who poses as Sudeikis and Aniston's daughter amidst their plan to ferry 1,400 pounds of marijuana from Mexico to the US.
Family photo: Eric Roberts posed for a photo with his daughter Emma and wife Eliza during a trip to Disneyland in February 2004
Killer role: Emma portrayed murderous high school student Jill Roberts in Scream 4