The Bisexual Spouse: Different Dimensions in Human Sexuality Edited by Ivan Hill Barlina Books, 264 pp., $16.95

Although most people today could probably identify more than one acquaintance they consider to be homosexual, very few would be likely to say they know even one bisexual person.

So it comes as something of a surprise that in a survey conducted by the Opinion Research Corp. in Princeton, N.J., and reprinted in its entirety in this book that nearly 66 percent of psychiatrists and 82 percent of sex therapists polled agreed that bisexuality exists in its own right -- not just as a compromise for closeted homosexuals.

But, these therapists say, the bisexuals they see in counseling almost always keep this information from their spouses.

Usually, this secrecy is based upon fear that the spouse would leave, taking any children away, and that public exposure would cause other problems professionally and possibly socially.

In "The Bisexual Spouse," editor-ethicist Ivan Hill has compiled poignant, albeit anonymous, interviews with male-female couples in which one partner suppressed and then realized an attraction to the same sex.

Frequently, Hill observes, those who are bisexual also report feelings of shame and guilt, although it's unclear whether these emotions are related to living dishonestly or to discomfort with their sexual selves.

Curiosity may lead many readers to this book, but ultimately the need to find clues to who becomes bisexual and why will engross the reader. However, Hill does not present easy answers to these complex questions. It is clearly not his intention to sensationalize bisexuality but to document this behavior.

While his own deep concern about the possible spread of the deadly AIDS virus through bisexual behavior is apparent, Hill also is unequivocally compassionate toward those who are striving to blend their alternative sexual identities with their chosen route of traditional heterosexual marriages.

Even though lesbian sexual activity would fall under Surgeon General Koop's category of "safe" sex, the sexual practices of an active bisexual married male could easily be a health threat for himself as well as an unsuspecting spouse.

Interviews with six couples detail the hidden lives of people who are seemingly average family members, friends or colleagues. But as the private side of their lives emerge, these couples report varying degrees of pain. For some bisexuals, there is the pain of living with suppressed desires. For others, there is the stress of leading clandestine lives, juggling intimate partners whose regard might shatter if the deception were known.

Beneath the surface, however, this sexual tug-of-war seems to be toughest for the straight spouse. If the wife is unaware of her husband's conflicts, she nevertheless may sense some inner emotional distance or be unable to understand certain moods or unexpected anger that often surfaces. If she does know, or merely surmises, that her husband is attracted to other men, she may go on trying to maintain the semblance of a happy marriage while taking on the burden of blame: "If only I were prettier . . . a better wife . . . more exciting."

Where the bisexual spouse is a woman, the eventual decision to declare openly her feelings for another woman led in most cases to divorce, although not as bitterly as when a gay husband left his marriage.

One problem with labeling people according to sexuality is that the categories may be too narrow. As one man explained: "The most accurate way to refer to myself is not to use the words heterosexual or homosexual. I am sexual . . . capable of an interest in sex with both sexes."

When the couples can no longer ignore the truth -- usually because of overt or increased homosexual activity -- 10 to 30 years together may have already passed. Most of the couples who were interviewed for this book are currently divorced, with the bisexual partner now living in a fully homosexual relationship. This may lead readers to question if this is an adequate sample from which to generalize about bisexual needs and patterns and to wonder if most bisexuals, once they have openly established a same-sex relationship, will begin a steady, if uneven, progression toward complete homosexuality.

Other couples interviewed who have kept their marriage together seem to consider bisexuality in an open marriage either as a minor flaw in a long, happy marriage or as a welcome dimension. In one case the husband claims, "Monogamy doesn't have to be limited to a physical relationship if respect and honesty are uppermost. My friendships with men are not the same commitment . . ."

Maybe not, but the real threat of AIDS certainly would seem to justify remaining monogamous, despite other proclivities, or at the very least being totally honest with a spouse. Bisexual activity, where one partner knows the risks and the other does not, removes intimacy and trust from the act of love and replaces it with cowardice. No matter what the real or imagined ramifications of openness about bisexuality, they cannot approach the certain dangers of silence.

Because the editor is the founder and president emeritus of the Ethics Resource Center in Washington and the author of "Common Sense and Everyday Ethics," readers may see this as a departure from his usual subject area. But considering the new dilemmas of sexuality today, who better than an ethicist to open the national discussion of bisexuality?Patricia M. Rice is a writer living in Springfield.