The pair, who recently rekindled their relationship following Stewart's affair with married director Rupert Sanders, are planning to spend the festive season apart after she spent a "nerve-wracking" Thanksgiving with his family in London last month, reported Showbiz spy.
"The family were smiling at Kristen and looking totally at ease on the red carpet during the 'Twilight Saga: Breaking Dawn Part 2' premiere but back at the family home over the following weekend things were more difficult.
"They had a meal on Thanksgiving and it was nerve-wracking for Kristen. She felt very uncomfortable and Rob's sisters couldn't be completely welcoming. It won't go back to normal straight away, even if Rob has decided to try again.
"Rob's family made it clear that they really want to see him over Christmas and, after the intense promotional tour for Twilight, Rob liked the idea of spending time alone with his family," a source said.