Bond, 35, was knocked unconscious in the crash but later woke and was able to call 911, Stewart's mother, Carol Stewart-Kosik, said.
Stewart's stepfather, Walter Kosik, said the couple have known each other since they were young children and used to go to church together.
"They have been friends the whole time, and they fell in love about 3 ½ years ago," Kosik said.
They were to be married at the Good Shepherd Lutheran Church in Pearl River, with a reception at a vineyard in Hillburn, he said.
Barbera declined to identify the other people aboard the boat and had no information on their conditions. He said the barge was equipped with lights, but it was still difficult to see on the water late at night.
The New York State Thruway Authority, which is overseeing the bridge project, said it was reviewing safety procedures.
"Our thoughts and prayers are with the victims and their families during this difficult time," the authority said in a statement. It added that the lighting on the barges appeared to be functioning normally.
Stewart's former English teacher at Pearl River High School, who remained in contact with her through Facebook, called the accident "heartbreaking."
"She was one of my students and a bright, sweet girl loved by everyone," said Doreen Arney. "I knew that she was getting married, and to Brian. To happen to two such special kids — it just shouldn't happen."