"There has been too much tragedy for them all," Mrs Stewart said.
"He was working that day but got out early because we had planned to go to Christchurch for a romantic weekend away. We got calls [about the explosion] as we were coming over [Arthur's] pass."
She expected many other miners would come over for her husband's "massive" funeral on Saturday.
He had been working as a foreman in Christchurch after the couple moved there to get work after the mining disaster.
Mrs Stewart, who visited the crash site on Tuesday, told Fairfax Media that her husband of three and a half years rode bikes as a hobby.
"It just shouldn't have happened.
"He was just such a caring, loving guy. He was very friendly and very much loved by a lot of people."
Police said Mr Stewart's family were "understandably upset" and were being supported by police and Victim Support.
The driver and sole occupant of the van was not injured in the crash.