Evelyn Lear and Thomas Stewart are opera singers, but their theme song could be George Gershwin's "Our Love Is Here to Stay." Gershwin, it turns out, was indirectly responsible for their meeting, as the two singers fell in love while working on a duet from "Porgy and Bess" at the Juilliard School of Music. The soprano and baritone recently celebrated their 44th wedding anniversary.

Although Lear and Stewart have sung leading roles in every major international opera house and share a gaggle of Grammys, things could have turned out differently. After graduating from Juilliard, Stewart was offered a position with then-fledgling IBM. While he mulled it over, he and Lear won Fulbright scholarships to study opera in Berlin. "It was luck that we both got it," says Stewart. If only one had received the award, they would have stayed put and perhaps Stewart would be talking about microchips instead of "The Magic Flute." Before the year-long scholarship expired, both snagged roles at the Berlin State Opera and their careers took off.

The couple spent the next 25 years in Europe. "It was the necessary thing to be done in order to make a career for us," says Lear. "There were so few opportunities for American singers." She became an expert in music by Strauss, while Stewart distinguished himself singing all four leading roles in Wagner's "Ring" Cycle. Stewart made his debut at the Met in 1966, and Lear followed a year later.

There has never been any "serious professional jealousy" between them, Stewart says, even after their Met debuts when the New York Times ran an article titled something like "Stewart Gets There First."

The couple, who have two children, made sure that their love for each other eclipsed their love of music. It helped that neither embraced the superstar attitude. "You've got to be really off the wall" to act like that, says Stewart, although he does confess they both have "strong personalities."

Although they no longer sing opera onstage, Lear and Stewart continue to perform character roles in operas and musicals. On Wednesday they will appear in a tribute to the late Patrick Hayes, founder of the Washington Performing Arts Society. While they might sing a note or two, their part of the program will be spoken and brief--they've been told they have about eight minutes on stage. The pair met Hayes in the '70s, when he hired Lear for a recital in Constitution Hall. Over the years they occasionally appeared on the WPAS schedule before Lear's retirement in 1985 and Stewart's in 1993.

Their most important professional activity these days is teaching master classes to aspiring opera singers. "We try to make them aware of what it means to be a performer," says Stewart. It's much more than "having a beautiful voice." Opera singers also have to know how to move onstage and understand the motivations of their characters.

While Lear grew up in a Brooklyn house brimming with music (her mother was an opera singer), her husband never saw an opera until he performed a small role in "The Marriage of Figaro." Ironically, Stewart, who grew up in San Saba, Tex., was encouraged in his love of the theater and Lear was not, for her mother had struggled in her career. "She didn't really believe I could do it until I did it," says Lear. "I was born for the stage--I'm a ham."

After Lear and Stewart moved back to the States in the mid-'70s, they watched with pleasure as opera became more and more accepted as an art form in this country. As the number of cities with opera companies grew, the popularity of radio and television made it easier for the music to be heard. The only barrier left, says Lear, is the often exorbitant price of seeing opera in person. But that will be another generation's battle to fight. Lear, 73, and Stewart, 72, occupy most of their time these days doting on their two grandchildren and playing golf. They divide their time between Rockville (near their son's family) and Florida, always following the sun. Stewart, for one, is pleased to be far from the big cities that once had his name in lights, preferring instead to spend evenings with his wife. Lear agrees. "We really like and love each other more now than when we were first married," she says.

The tribute to Patrick Hayes takes place Wednesday at 8:30 p.m. at the Kennedy Center Concert Hall. Tickets are $10. 202-833-9800.

Arts Bits

Eighty-one of Helen Kornblum's vintage photographs are on view at the recently opened show "Defining Eye: Women Photographers of the Twentieth Century," at the National Museum of Women in the Arts. Today at noon, Kornblum, a psychotherapist, will give a free talk about her collection. At the museum, 1250 New York Ave. NW. For information, call 202-783-7370 . . . This afternoon at 12:30, Sidney Lawrence will moderate a panel discussion titled "Artists on Beauty," with artists and curators of the show "Regarding Beauty" at the Hirshhorn. The talk takes place at the museum's Ring Auditorium, Independence Avenue and Seventh St. SW. For information, call 202-357-2700.