The studio executives have been hoping Pattinson can forgive Stewart for cheating on him with director Rupert Sanders and patch up to promote "Breaking Dawn Part 2", New York Post reported.
The couple met on the sets of the first film "Twilight" back in 2008 and their off-screen romance has played a huge role in the obsessive fan-driven success of the franchise.
The fifth instalment of the saga, "Breaking Dawn Part 2," is due in theaters in November and distributor bosses are concerned that Stewart's public image would be a negative influence on their promotional tours.
"The studio's holding out to see if they get back together. But I don't think anyone is banking on that happening. At this point, the press strategy would have been mapped out. It's usually very organised, but at this time it's undecided," a source said.
Stewart and Pattinson could attend premieres separately if they don't reunite.
The company has also planned to keep actress Ashley Green, who plays the role of Alice in the film, as an option to head the promotions in case things don't workout between the lead pair.
