It is said that for every problem there is a solution and for every solution there is a problem. The problem of AIDS is being solved in part by a new monogamy in relationships and marriage. While not denying the deadly seriousness of AIDS, one of the ways we cope is by looking at the lighter side. What would an Agatha Christie sleuth say about the monogamy being fostered by the current AIDS crisis?

Indeed, the days of singles on the prowl may soon be over. I heard there was recently a solemn occasion at Hains Point when a line of seven men walked somberly to the Potomac River and ceremoniously tossed in their well-thumbed little black books and handfuls of business cards they got from networking.

Meanwhile, the singles bars seem deserted. A friend walking past a Southwest "meet market" Thursday night was shocked to find the usually thriving bar emptier than a church on Monday afternoon. In fact, church is where some men are going -- they don't want to meet girls unless they're good and they're properly introduced.

Furthermore, have you noticed that a lot of men aren't wearing those tightfitting jeans anymore? And I haven't heard anybody talking about "man-sharing" lately. The new monogamy is even affecting people's travel personalities as well -- tourism seems to be down. Where once men and women used to talk about going to Rio for carnival, Mardi Gras and a sexual dalliance, now they are staying at home watching National Geographic specials and thumbing through magazines with big picture layouts.

Not all men are taking this state of affairs without a fight; a few adventurous single men have slipped a card showing they passed their AIDS test into their wallets alongside their credit cards, and they flash it whenever some brave woman shows an interest in them. But one of my friends said: "I have to feel sorry for people who are not married right now; they're the ones going through hell. Every time they meet someone, they have to wonder, 'Is this the bullet with my name on it?' "

But it is not only among single people that a new monogamy and carefulness in sexual behavior can be seen; my married friends say their lives have changed as well. My girlfriend says that where once her husband used to tell her he was going to "evening meetings" and "late-night conferences," he now sits moping around the kitchen all evening.

Another friend says of her husband, "He looks lost. He used to rush out energetically in the morning and come back so exhausted (but strangely exhilarated) that I had to help him out of his clothes so he could crash into bed at night." Now, she says, the situation is reversed. "He gets up in the morning and drags out to work and late at night he has all kinds of energy."

Yet another friend says her husband has even dropped his subscriptions to Playboy and Penthouse. "He just sits around, watching TV shows like 'Bill Cosby' and 'L.A. Law.' "

Why, there's even been a decline in the divorce rate, and a friend who recently visited Virginia Beach said he saw more families on the beach than ever before.

Thousands of men, realizing they couldn't do the things they used to do, looked forward to the start of the football season when they could at least go to a bar, cheer the Redskins on TV, sit around with friends and sip a beer. Now, sadly, all they can do is go to the bar and grudgingly watch Redskins substitutes.

But the new AIDS-prompted monogamy isn't just changing men's behavior nationally; it's happening internationally as well. One small indicator of what is to come in Africa may be the situation recently recounted by a girlfriend from Zaire. She said some husbands are now nervously underfoot at home so much it's driving the women crazy. On that continent, the problems are even worse than in Washington because acquired immune deficiency syndrome is affecting the heterosexual population more and men and women equally, and the World Health Organization estimates that at least 50,000 men and women have AIDS symptoms and 2 million or more are infected with the virus.

Quite frankly, most of the women I know would rather have a cure for AIDS than a monogamous mate or a swinging life style. Yet the question I'm moved to ask now is, "Is disease the key to fidelity?" Were some of the men in generations past faithful only because they were afraid of getting syphilis or gonorrhea?