"Before we went on the Marriage Encounter weekend," says Don Thieme of Alexandria, "we thought we had a good marriage. When we reached those rough spots we would talk for hours on end.

"Yet as we look back on it there was quantity in our discussions, but there wasn't quality -- because we weren't able to sort out the difference between feelings, judgments and attitudes. We didn't realize that feelings aren't right or wrong, they just occur. And we weren't able to listen to each other's feelings without making judgments on them."

After experiencing their first Worldwide Marriage Encounter retreat through a Catholic church in Tallahassee, Fla., the 46-year-old Thieme (pronounced THEE me), who came to Washington to work as an AID administrator for the first Reagan administration, and his wife Carole, a 41-year-old commercial artist, linked up with a Washington-area branch of National Marriage Encounter when friends invited them to a monthly gathering of couples who have "made a weekend." These small-group meetings help couples refine skills to work through what Thieme calls "that constant evolving cycle of romance, disillusionment and joy."

A lot of people get the wrong impression because of the name, says Lutheran Marriage Encounter coordinator Jake Rabatin, 46, Manassas, a Defense Department electronics engineer. "It's not an encounter group."

In Marriage Encounter (unlike Marriage Enrichment) there is little or no group interaction. Couples gather for short talks given by the team leaders; the only interaction that takes place after that is between each couple, out of sight and hearing of other couples.

Nor is there confrontation. Blaming, judging, diagnosing, even persuading, are taboos.

"It's not a vacation weekend, either," says Rabatin, to correct another misconception, "where you have a lot of time to golf or swim. It's a working weekend."

Marriage encounter takes its name from the Spanish word encuentro, for rediscovery. The idea is to provide a peaceful, nonthreatening setting and format that will help participants reflect on their attitudes toward themselves and their partners, their families and the outside world, and to talk more openly than they usually do about their hurts, desires, expectations, joys, frustrations and disappointments.

The weekend typically begins with anywhere from four to 35 couples (in some groups, a minimum of 20) gathering Friday night in a meeting room at a motel or retreat house. The format for that evening and the rest of the weekend is to alternate between short talks, to which the whole group listens, and short, private "dialoguing" -- a verb in these circles -- sessions between each husband and wife. One, two, or three couples give the talks, often with a representative of the clergy.

Topics are chosen to elicit greater individual and couple self-awareness, with team couples drawing heavily from their own experiences to help new couples overcome fear of self-disclosure.

"Many married people shrink from this," writes David R. Mace, author of Close Companions: The Marriage Enrichment Handbook (Continuum, $17.50), "thinking that if they were in fact fully known they would not be loved, but rejected."

But in marriage, writes one of the leaders in the Marriage Enrichment movement, "Love is not dependable if it's based on partial knowledge. The only basis for a secure sense of identity and self-worth is the knowledge that you are fully known and at the same time deeply loved."

After a period for reflection, husbands and wives are asked to write down their thoughts and feelings on subjects such as: "What do you see as your pluses and minuses?" "What kind of mask do you wear with your spouse?" "What roles have you inherited from your parents?" "How do I feel about having committed myself to a lifetime with you?"

After writing for 10 to 35 minutes on each subject, husband and wife exchange notebooks or "love letters," and after reading what each has written they talk about it. Although some people may be put off initially by the thought of letter-writing, for many couples, say participants, the "10 and 10" (at least 10 minutes of writing, followed by 10 minutes of talk) is a liberating experience, a form of sharing they are urged to continue.

"Carole and I had a real good fight on the way to the motel," recalls Thieme, "a disagreement about how to handle the disciplining of the children. I remember going into the meeting room thinking maybe this wouldn't be such a good experience for us.

"By Saturday morning we were totally immersed in the process. Sometimes we were irritated that we had only 10 minutes to write, because we had so much more to share with each other. And it just kind of mushrooms. By Sunday afternoon we walked out of our room and for a moment in time I had lost touch with what day it was and where we were."

The focus of Marriage Encounter and Marriage Enrichment weekends is on prevention rather than cure: on the healthy, well-functioning couple experiencing some alienation rather than on the seriously troubled couple. The team leaders who run these groups are not trained therapists, and couples experiencing serious problems are advised to seek professional help.

Team leaders have occasionally been called to task for their amateur status by critics of marriage encounter. Among them: David Olson, professor of family social science at the University of Minnesota, and William Doherty, a professor of family practice at the University of Oklahoma. After surveying couples who had attended marriage encounter weekends, Olson concluded that "while a marriage enrichment program increases a couple's motivation to improve their relationship, it does not provide them with the skills they need."

Prof. Doherty wrote in the American Journal of Family Therapy that 9 percent of the couples he surveyed found it harder rather than easier to express their feelings after a marriage encounter weekend. Doherty also complained, in the National Catholic Reporter, that the weekends raised the hopes of some couples, who were later disappointed when their marriages didn't change according to their expectations.

Counters Nancy Kennedy, a 41-year-old Rockville, Md., housewife: "The people whose expectations are disappointed are those who go for the weekend and don't continue working on the marriage. We went on our first Worldwide Marriage Encounter weekend seven years ago, and we've done the 10 and 10 regularly since then."

David and Vera Mace, Winston Salem, N.C., former directors of the American Association for Marriage and Family Therapy, acknowledge that the response of the average couple invited to a weekend is, "We don't need that kind of thing."

For many, expressing the desire to improve the marriage implies that it's in trouble, which in our culture "carries a subtle suggestion of incompetence and humiliation."

Yet thousands of couples -- some say 2 million worldwide -- have experienced some form of marriage encounter, and it's hard to find a more enthusiastic booster group.

Says Nancy Kennedy, "Eighty to 90 percent of the people who come off a weekend say something like, 'I wish I had done this five years ago when my cousin in New Jersey told me about it.' "

Explains her husband, Bernie Kennedy, 42, a systems analyst for the Montgomery County Board of Education: "A lot of people are comfortable in the marriage. They've learned to dance around the hot-button topics."

Though she admits she was reluctant to go at first, "I think it really brings the dream alive again of how you were when you were engaged," says Nancy Kennedy. "The sky suddenly looks bluer."