Pattinson told reporters at Breaking Dawn's LA premiere that Stewart took the movie's pivotal wedding scene very seriously.
"It was very sweet. I hadn't been nervous for the entire scene before [she walked down the aisle]," the actor told Entertainment Tonight.
He added: "I was just sort of standing there like not really doing anything, and she walks out and she's looking absolutely terrified."
Pattinson further commented that he was ultimately pleased with Bella and Edward's nuptials, adding that Stewart looked "incredible" wearing a white wedding dress.
Stewart previously remarked that shooting Breaking Dawn's wedding felt like a tremendous accomplishment.
The Twilight Saga: Breaking Dawn - Part 1 is released in cinemas worldwide on November 18.
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Watch a trailer for The Twilight Saga: Breaking Dawn - Part 1 below: