Friends of Rihanna and Chris Brown are reportedly "terrified” that the pair will reunite.The former couple, who split in 2009 after Brown assaulted the ‘We Found Love’ singer, have been romantically linked on several occasions - most recently at Rihanna’s 24th birthday party in LA last week, where they were described as having "coupled up”.Sources say that friends of both stars fear that the release of their ‘Birthday Cake’ and ‘Turn Up The Music’ collaborations this week marks the beginning of a relationship that could damage them personally and professionally.According to TMZ, Rihanna has said that she would be back with Brown if it were not for the media and her fans, while the ‘Yeah 3x’ singer is prepared to cool his romance with model Karrueche Tran for a potential reconciliation.A source noted to the website: "You can’t hold back love.”Brown was sentenced to 180 days of community labour and five years’ probation after pleading guilty to assaulting Rihanna. AP.