Dr Koornhof should know about apartheid - as a Nationalist cabinet minister he was once in charge of enforcing it. But 18 months ago he shocked Afrikaner society by leaving his wife for Ms Adams. Not only was she 44 years younger and pregnant by another man, but she was of mixed race, or Coloured in apartheid parlance. They hope to marry soon.
'Once we could have been jailed,' Ms Adams' 68-year-old lover said happily. 'But I can honestly say I have risen above colour. It is a fantastic experience, one which I wish everyone in South Africa could have.'
Dr Koornhof's optimism about the future was enhanced by the news that Chief Mangosuthu Buthelezi's Inkatha movement will take part in the election. Ms Adams had been talking of voting Nationalist, but now planned to back Chief Buthelezi. 'I am very sensitive to surroundings and auras, and I was very impressed when I met him with Piet,' she said. Dr Koornhof may do the same. 'I have not ruled out voting for the ANC,' he said.
This is clearly not the same man who, as deputy minister of 'Bantu' (black) administration, told a Nationalist rally in 1982: 'I don't want to do anything detrimental to the South African economy, or be unfair to the Bantu, but there is something that must be stopped. We don't allow Bantu typists and so on working with white women in the same office, and I am going to stop it.' Now he is living with Ms Adams.
According to Dr Koornhof, his opposition to apartheid has been consistent. Why then, had he served the system so long, as a minister for 18 years and as South African ambassador in Washington from 1986 to 1991?
'The answer is very simple. When I was a Rhodes Scholar I met King George VI and later I went to his funeral. I had been offered a lectureship at Oxford, and was weighing that up, but before the funeral I spent time with other people from many countries who had also come to attend. It dawned on me that I must try in whatever modest way I could to bring about better understanding in my country.'
Dr Koornhof used to weave similar verbal webs when he was minister for sport, trying to reconcile white South Africans' yearning for international competition with his colleagues' refusal to yield the concessions that might have made it possible. Later, as minister of 'co-operation and development' - black affairs under another name - he was nicknamed 'Piet Promises' for his assurances that apartheid would soon be a thing of the past.
He resents being described as an architect of apartheid. 'I was from the generation that inherited the policy, and I tried to reform it from within'.
Although his relationship with Ms Adams has led to death threats, Dr Koornhof says it has rejuvenated him. 'We hope to have children together - nothing would make me happier. . . she has brought me to all the places I couldn't go as a cabinet minister. Today they are my friends.'