Maybe when she realized that she was 49 years old and that the kids were now in school all day, and she found herself having to fill hours that had once taken care of themselves, maybe, Cynthia Dwyer's husband admits, that's when she decided to go.

Whatever her reasons, in April 1980, the Buffalo, N.Y., housewife, who had never before written a news story as a professional journalist, declared herself a free-lance foreign correspondent and flew to Iran. There, she promised, she would write about Iran's struggle for freedom that had been forgotten since the American hostages had been seized.

Two weeks later she was arrested by Islamic Guards in her Teheran hotel room, accused of being a CIA spy, and thrown into prison. And there she has remained, becoming what some now call America's 53rd hostagee.

Dwyer's case has really only captured the attention of most Americans since the release last week of the 52 hostages. Unlike those seized in the embassy, she has been isolated from other Americans. For seven months no one was even permitted to visit her.She has been permitted to send and receive only a handful of letters.

Negotiations for her release have been difficult. The State Department has had to rely on the Swiss Embassy, which until last week was preoccupied with the 52 hostages. Now, the sudden interest in Dwyer, coupled with Iranian defensiveness over allegations that the ex-hostages suffered psychological -- if not physical -- torture, has only complicated matters, sources say.

At the same time, because of a long-standing policy against commenting on anything related to intelligence matters, the State Department is in the curious position of being unable to deny or confirm that the Buffalo housewife is a CIA agent.

But as one official said, "I think the forcefulness of Mr. Dwyer's denial [that she is a CIA agent] and Mrs. Dwyer's own personal circumstances prior to going to Iran ought to tell you something."

Dwyer's journey to Iran is a uniquely American one, full of the same vintage liberalism and idealism -- and naivete -- that inspired another housewife, Viola Liuzzo, to leave her Detroit home in the 1960s and join the civil rights freedom marches in the South. In 1965, they also led Liuzzo to an Alabama back road where she was murdered.

In the case of Dwyer, who is the wife of an English professor at Buffalo State College, her fascination with Iran began after the downfall of the shah. She frequently spoke with Iranian students and acquaintances, according to her husband, John F. Dwyer, and mother, Mildred Brown.

The Iranians told her of their hatred for the shah and his regime, which they said routinely used tortune and political oppression to keep control.

It touched a sensitive chord in Dwyer, both say.

"Cynthia was always for the underdog," said her 77-year-old mother, who lives in the small town of Horatio, Ark. "It was just the thing that was natural about her. I remember when we first moved to Bastrop [a Louisiana mill town] in the '40s. The place was over half black, and when she'd see the white children teasing the black children, she'd ask, 'Mother, I don't know why they do that.'"

Her husband, whom she married in 1965, said that, shortly after he first met her in Chicago, he opened a Chicago newspaper one morning to find a letter to the editor she had written.

"It was about some tobacco subsidy," he recalled. "She was complaining about how the government was subsidizing this industry at the expense of the ordinary person. I thought [the coincidence] was pretty funny."

But Dwyer took her convictions seriously. Even after they were married and she quit her job as an editor for a publishing company to devote herself to raising three children, she continued to pepper the editorial pages of newspapers around the country with letters. The thrust was always the same: the little man, the man who espouses sometimes unpopular causes, groups with different creeds or ethnic backgrounds, all these were being harmed or discriminated against by government or society.

Her last such letter, written a few months after the taking of the American hostages, appeared in the Monroe (La.) News Star. The letter was prompted by reports that a number of Iranian students at a Louisiana college has been arrested after they had protested the appearance on campus of a former official of the shah's government.

"U.S. Citizen Befriends Iranians," was the headline over the letter.

"I have found all [Iranians] to be as kind and gracious as any group of people I have met anywhere," she wrote. "None of them are hapy about the taking and holding of hostages."

She argued that the Iranian students arrested at the college should not become scapegoats for American frustration in trying to resolve the hostage crisis. "They are our guests in our country, and we must extend to them every guarantee of our Bill of Rights," Dwyer insisted.

Her letter concluded, "Finally, let me add that the Iranian government has granted me a visa to travel freely and to report on what I see in Iran in April [1980]. I believe that the hostage crisis is nearing an end, that both governments shall have learned something important from this travail of the 50 [sic] Americans and that America can live in peace with Iran."

Her mother says it was she who made it possible for Dwyer to go to Iran. "I helped her. I had just turned over $5,000 from a paid-up life insurance policy," she said. When that turned out not to be enough, "I gave her some more."

But she did it reluctantly. "I told her, 'Cynthia, I wish you wouldn't go. I don't think you ought to leave the children. It's so dangerous over there." She said, 'Mother, you never wanted me to do anything. '"

Her husband was reluctant, too, "but there didn't seem to be any real danger," he said. "It wasn't like going into El Salvador. Besides, it meant a great deal to her to go.

"So she went."

In the months since she was arrested, her husband has talked personally with then-Secretary of State Edmund S. Muskie and taken the children to Washington to meet with Swiss embassy and State Department officials.

"It's been 8-1/2 months now," he said. "And it's never been easy. But I was ecstatic when they released the hostages. When I saw them come down the plane ram, when I saw the families, I knew what they were feeling. And they know what I'm feeling."

The State Department says it has been notified through the Swiss that the Iranian government has not yet completed its investigation into Dwyer's case. When that is completed, it said, perhaps she will be freed.

"I've become pretty fatalistic," her husband said. "Because of what happens to people and because of how little control we have over our lives. It makes the future seem somehow not important. It makes a lot of things seem relatively unimportant ."