You may question what could possibly make theater out of an evening in which two soap opera stars simply chat and sing "about love." No plot - "the plot is love," said the co-star and writer, Don Hastings.

But it would be hard to question whether they know their subject.

Hastings and Kathryn Hays, who will perform "Hastings & Hays On Love" at the University of Maryland's Tawes Theatre at 7 tonight and 4 p.m. Sunday, play Dr. Bob Hughes and Kim Steward on the daytime serial, "As The World Turns."

Their combined experience of love and marriage is astounding. (This is assuming, of course, that you confuse the actors with their television roles, which everybody always does. In fact, Hastings mentions that as a motivation for doing theater - "people will know me as Don Hastings, not just as Dr. Bob." Or maybe the other way around, but you get the idea.)

Dr. Hughes married Lisa when he was in medical school and interning. "I was so dedicated to my profession that I neglected her. We have a son who's not quite as old as I am, but he's catching up. He was born 16 years ago, and he's practicing attorney and has been married twice.

"I then married Sandy, a girl from the other side of the tracks who had great ambitions of being a model or an actress. Socially, she wasn't Bob's equal, and also she was hurt in a fire and had mental problems. She disappeared. I divorced her a respectable period of time after that - about six hours.

"Then I married the girl in my dreams, Jennifer."

Jennifer's sister, Kim, played by Kathryn Hays or the other way round, now entered the scene. She was the widow of Jason Reynolds, an "older"businessman. She came to live with Bob Hughes and Jennifer, got interested in Bob and showed up in the same hotel with when he went to Florida to make a house call on a patient after Jennifer had disappeared from home, as a result of marital problems instigated by her son from a previous marriage.

Jennifer and Bob - notice we are now talking about Hays & Hastings - had what he describes as "one night of love," which left her pregnant. When he went home, he found his wife - and her sister - had reappeared, and was also pregnant. "There were girls at CBS who wouldn't get in the same elevator with me," said Hastings.

Kim needed a husband, so she married Dr. John Dixon, whom Hastings described as a "baddie - an opportunist." The husband, mind you. Anyway, the baby was miscarried, a medical phenomenon with illegitimate pregnancies which is well know to soap opera doctors, and Kim got pregnant by Dixon, whom she then divorced, marrying Dr. Dan Stewart.

Hastings was asked if that was a happy marriage. "Oh, yes. Of course, they've only have been married an hour and a half, so something may yet go wrong."

Bob is now unmarried, Jennifer having died in an automobile accident. He - Hastings - was asked what he had learned about marriage in 17 years of "As the World Turns."

"I learned that if you have a happy marriage, watch out. You're going to get written out of the script."