JOHANNESBURG -- It's without a doubt the romance of the year in South Africa, and some see it as the avatar of the new racial social order slowly emerging from this rigidly segregated society.

Whites here were flabbergasted last month when they started reading stories about the supposed engagement of President Frederik W. de Klerk's son Willem to a mixed-raced beauty, Erica Adams.

The story had white society all atwitter, and not just because Willem is the president's son and Erica the daughter of a mixed-race politician from Cape Town, Deon Adams. Willem's parents, it is alleged, knew nothing about the relationship until a jewelry store called up to find out who was going to pay for the expensive diamond engagement ring their son had just bought.

Mother Marike, noted for her strong Afrikaner moralistic streak, was immediately reported to be severely "distressed" and up in arms about her son's liaison dangereuse.

Also unbeknownst to most South Africans until news of the romance broke was the fact that Willem, as well as his older brother, Jan, and sister, Susan, is an adopted child. This explained why the boyish, bespectacled Willem, whose face suddenly was appearing everywhere, seemed to bear such little resemblance to his father.

For South Africa's sensationalist press it was the juiciest love story in years, particularly since it could be portrayed as the perfect symbol of the fast-changing times here. What better proof that President de Klerk was serious about doing away with apartheid than allowing his son to date, and maybe marry, a "colored" beauty.

But the nagging question right from the start was, "Do the parents really approve -- or will they interfere to break up the whole romance before it gets to the altar?"

The hot gossip spread across South Africa's daily and Sunday papers throughout January was that Marike de Klerk was working day and night behind the scene to do just that. It was even said she had shipped her 24-year-old son off to England "to cool down his love," as the Sunday Star put it.

Erica's parents seem equally distressed but it is not altogether clear whether this is because of her romance with Willem or the pressure they are reported to be under from Marike de Klerk. Adams's father is a deputy in the segregated House of Representatives, one of the three bodies making up the South Africa tricameral parliament.

The president appears to be much more philosophical than his wife about the romance, at least on the surface. On Jan. 13, he authorized a statement saying Willem had informed him -- when was not clear -- that he was "considering getting engaged. In fact, I only recently became aware of the existence of a relationship between him and a student friend." The statement continued:

"My son is 24 years old and has been out of the house for quite a while already. As an adult man he is in a position to take decisions on his own. I regard the matter as a private family matter and I believe it should be handled as such."

De Klerk must have been dreaming if he really thought an engagement between his own son and a woman of color could be kept "a private family matter," particularly in a year when he himself is instituting reforms to bring the walls of apartheid tumbling down around white society.

The dailies here have had a field day splashing all over their pages pictures of the two in various romantic poses, hand-in-hand, head-against-head and lip-to-lip.

Erica, also 24, who has long black hair, vaguely Asian features and a model's body, at first played coy with the press after the story of her romance broke Jan. 10 here and in London.

But there is now a sneaking suspicion she may have been doing this just to boost the price of "exclusive" interviews she has given to various British and South African newspapers. Suddenly there she was on the front page of the Johannesburg Sunday Times Jan. 27, wearing a seductive black cocktail minidress with a plunging neckline and telling all about her eternal love for Willem.

Inside were several other pictures of her, or the two of them together, that did nothing to thwart her hopes of becoming a professional model.

The country's 2 million "coloreds" are brown-skinned descendants of three centuries of interracial affairs between South African blacks and Dutch, French and German settlers. They are the closest class -- culturally and in skin color -- to the 2 million to 3 million ruling white Afrikaners. They speak Afrikaans and share the same God-fearing Dutch Reformed Church religion. They sing the same folk songs, read the same poets, have the same names.

The coloreds are sometimes called "brown Afrikaners" but they don't really fit into either black or white society here, which is why they are also sometimes called "God's stepchildren." Still, they are the third largest racial group in the country. Unlike South African blacks, coloreds can vote -- but only for members of their own segregated legislature. Like blacks, they cannot live wherever they wish; at least for the moment, housing remains segregated.

Mixed marriages in puritanical traditional Afrikaner society remain taboo and were actually illegal until just a few years ago.

It was de Klerk's own National Party that, within a year of its triumph at the polls in 1948, pushed through the Prohibition of Mixed Marriages Act. As if this wasn't enough, in 1957 it passed the Immorality Amendment Act forbidding "unlawful carnal intercourse" or "any immoral or indecent act" between a white and nonwhite.

Prophetically enough, it was none other than de Klerk who in April 1985, as home affairs minister, stood up in Parliament to declare that "the most controversial laws on the South African statute book" were about to be scrapped. He was referring to both the prohibition on mixed marriages and interracial sex.

De Klerk said the government had concluded the laws were no longer essential to preserve group identity and was "committed to the goal of eliminating racial discrimination." Right-wing whites denounced the move and warned it would endanger the "national identity" of the ruling Afrikaner minority.

The repeal of the laws hasn't exactly led to a flood of mixed marriages. The Central Statistical Service reported last March that in 1988 1,076 mixed couples got married, including 302 whites with coloreds, by far the largest combination of any.

The most celebrated white-colored marriage scheduled for this year -- and the great romance scandal of last summer -- is that of the Rev. Allan Boesak, former head of the colored branch of the Dutch Reformed Church and the World Alliance of Reformed Churches. Boesak has given up his lifelong career in the pulpit and as an internationally renowned anti-apartheid activist, resigned all his church positions and gotten a divorce so that he can marry a popular Afrikaner television personality, Elna Botha, on Feb. 23.

The history of the student romance between Willem and Erica has been coming out in bits and pieces from friends, and from the couple themselves, in various interviews. They told the Sunday Times that they first met about two years ago totally by chance at Jan Smuts Airport here while waiting for a plane to Cape Town. They sat together during the two-hour flight, talking, discovering they both were attending Cape Technikon, a college outside Cape Town.

Both were studying public relations, but Adams had already attended Stellenbosch University, the elite Afrikaner institution, for three years.

Attending Stellenbosch was already quite an achievement for a colored woman but Erica had also distinguished herself there by becoming a semifinalist in a beauty contest.

Willem, according to other press reports, had just broken up with another girlfriend. He and Adams found they had three things in common, according to one report: They were the same age, studying the same public relations course, and liked to party.

Erica was quoted by the London Mirror as saying that "everyone {at school} knows about our relationship." But apparently nobody ever told Willem's parents. In fact, Adams told the Sunday Times she has never been invited to meet his parents and he has only once been to her home.

Erica seems to be thriving on the publicity, offering to pose for various newspapers and telling reporters how much she loves Willem and misses him while he is away in England attending the Cambridge Business College.

The tantalizing question on the minds of many South Africans: Will love conquer all? Will President de Klerk, already decried as "a traitor" to his party and church by white conservatives, decide to take the additional political heat and stand aside? Or will Marike, dead set against the marriage, have her way?

Erica doesn't seem too shy to talk about their dilemma. "We hope we will stay together," she said in the interview appearing in the Sunday Times. "We both come from strict, religious families and I will only have a baby in a marriage. If Willem asked me to marry him, I know what I would say."

No, she wouldn't say.

As for her second-class citizenship, Erica said she would like to have "all the rights that Willem has" and to see mixed-raced couples "live where they like" and their children "able to vote."

In the same interview, Willem confirmed that "we are in love." But he didn't indicate whether he intends to ask Erica to marry him.

Willem has been in England since December. By his own admission, he has spent a lot of time on the phone talking to Erica, who finally made a trip there to see him in a "secret hideaway," where they were interviewed by one or more newspapers in late January.

At a press conference in Cambridge Jan. 11, he refused to confirm that he had given Erica the diamond ring or 'fess up to anything more than "a friendship."

"The laws over mixed marriages only changed six years ago but I don't think anyone has ever gone to jail for being friends with someone of another race," he said.

At that point, only a few days after his romance with Erica had become known, he seemed surprised by all the fuss.

"I never thought it would get this big," he remarked. "I knew people in South Africa would be interested but not the rest of the world."