Demong intended to propose to long-time girlfriend Katie Koczynski and had been carrying an engagement ring around with him for months.
Demong eventually decided to pop the question following Thursday's individual hill competition.
"A little part of me really wanted to win to make it that much better," Demong said.
Later on Thursday, gold medal safely secured, Demong called Koczynski onto the stage at the team's headquarters, went down on bended knee and proposed. She accepted.
There was a slight hiccup.
"An old gymnastics injury on her ring finger made it tough, but (Demong) teammate Todd Lodwick stepped in to help squeeze the ring onto her finger," he added.
Even more good news was to come. Demong, will be the US flag bearer in Sunday's closing ceremony.
His gold was the first for the United States in an Olympic Nordic Combined event, which features a ski jump and a 10 km cross country race. Demong won a silver in the team event.