ATLANTA, AUG. 2 -- When Atlanta Archbishop Eugene A. Marino resigned unexpectedly last month, much was made here of the strain put on the nation's first black Roman Catholic archbishop.

Hundreds of speeches and constant travel had taken their toll; the popular archbishop, one of the most important Catholic bishops in the United States, finally collapsed, friends said. The Atlanta Constitution, in a flattering profile, described him as a man so generous with his time he "could not say no."

So Catholics here were stunned almost to the point of disbelief when church officials admitted Wednesday that Marino stepped down because of a two-year affair with a singer who once filed an unsuccessful paternity suit against another priest.

At a jammed news conference, church officials today added little to the details of the scandal, other than to confirm that the romance began shortly after Marino arrived in Atlanta from Washington in May 1988, endured during the next two years, and is now over.

Marino was auxiliary bishop for 12 years and served as pastor of St. Gabriel's Parish before taking over the Atlanta archdiocese.

Vicki R. Long, 27, the woman involved with the archbishop, 56, was described in newspaper accounts as a "kind of Catholic camp follower." A former hospital employee in Columbus, Ga., Long filed suit in 1987 against a Georgia priest, the Rev. Donal Keohane, charging that he had fathered her child. (Blood tests indicated that he was not the father.) She reportedly was last seen attending mass in Hapeville, Ga., last Sunday, where she is a lay minister.

One photograph of the couple seated at a banquet appeared on Atlanta television this week, and some say their close friendship was not secret. But others, such as Roland Blanding, formerly a top black leader in the Atlanta archdiocese, said the news of Marino's relationship had left him in "absolute shock."

No one he knew suspected anything, he said. Blanding played down the fact that television had a photograph of Marino and Long together at a church banquet. "Marino took pictures with a lot of people at that same event," Blanding said.

The scandal particularly hurts black Catholics, he said. "It just seems that whenever it's a black leader getting in trouble, it's made public," he said.

Bishop James P. Lyke, who is expected to succeed Marino, defended the church's decision not to reveal earlier the nature of Marino's resignation.

"When Archbishop Marino's resignation was made public on July 10, he stated that it was for personal reasons and that he was pursuing appropriate spiritual, medical and psychological therapy. That was true," Lyke said. "What was not announced, however, was that the personal reasons involved an intimate relationship with a woman."

Catholic priests take a vow of celibacy. Church sources in Washington said they heard Marino's departure was prompted in part by Long's demand that the church pay her money to keep quiet about her relationship with the archbishop. Marino would not pay, they said, and decided to resign before Long or someone else made the relationship public.

But Lyke emphatically denied reports that church funds were paid to Long to cover her personal expenses, child care and mortgage payments.

However, he said that for reasons of charity, church funds were used to cover some of Long's medical expenses, although he declined to say how much or describe Long's medical treatment.

WAGA-TV in Atlanta reported Wednesday that the archbishop helped Long buy a house and contributed at least $1,500 a month to her living expenses and bought flight insurance policies naming her as the beneficiary.

Lyke said that Marino, who is paid a salary of $1,500 a month, may have used personal money.

Lyke said at the end of April, Marino told him "he was experiencing great stress and was overworked and would take a leave of absence."

In May, Lyke said, Marino informed archdiocesan officials "of the facts" and stepped down temporarily while the matter was reviewed.

The matter eventually was reviewed by the apostolic pro-nuncio, Pope John Paul II's representative in Washington, Lyke said. A spokeswoman in the pro-nuncio's office said no one could comment on the Marino matter.

There have been "two or three other cases" of Catholic bishops resigning after affairs with women, according to church historian Msgr. John Tracy Ellis. In one such case in the late 1960s, an auxiliary bishop of St. Paul, the Rev. James Shannon, left the priesthood and got married.

Priests who know Marino, now at a treatment center in New York state, said they do not believe he will shed his collar.

Marino, a recovering alcoholic who spoke openly of his 12 years of sobriety, had not resumed drinking, church officials said.Staff writer Laura Sessions Stepp contributed to this report from Washington.