Still, the couple honor Petersen's five years of military service every November 11.
"Yes," Lighty interjected, "on Veterans Day, I have to stand up very straight and say, 'Ma'am!' all day long."
Petersen added: "She has to say, 'Good morning, captain!' Lots of respect, and that has gone on for 35 years."
On their blind date at 5 p.m. on January 13, 1977, the couple rendezvoused for supper at an old town restaurant in Sacramento, California.
A mutual friend arranged the date.
Lighty cheated that evening: "I stayed in the parking lot to see what she looked like as she got of the car," she said. "I said she's cute and she's short."
Dinner was a success.
"Boy, we just hit it off," Petersen said.
Two weeks later, they moved in together.
Lighty had earlier been married to a man for two years. Petersen had adopted and was raising her sister's 10-year-old daughter. Their home also had two dogs and a cat.
The couple wondered what they had gotten themselves into.
At the time, Petersen and Lighty were nurses. In fact, Petersen was working in public health nursing, and was California's first nursing home ombudsman for the state Department of Public Health under then-Gov. Ronald Reagan, she said.
By 1986, they had moved to Seattle, where they slowly came out of the closet in the late 1990s.
First, they supported a gay men's choral group called the Seattle Men's Chorus. By the early 2000s, they started a lesbian counterpart, the Seattle Women's Chorus.
In 2005, they announced to the world that they were longtime partners by participating in the documentary "Inlaws & Outlaws," which examines the lives of straight and gay couples.
On Sunday, the couple will marry onstage before the Seattle Men's Chorus and Seattle Women's Chorus at Benaroya Hall, home to the Seattle Symphony Orchestra.
Two men who have been together for 23 years will also marry onstage, the two women said.
When Petersen and Lighty tie the knot, the Women's Chorus will be singing from "One Hand, One Heart" from "West Side Story."
As they approach the 36-year mark of being a couple, Petersen observed: "We're just blessed with the people we've met and the opportunities we've had."