Oprah Winfrey's fiance is preparing for them to finally marry, more than 20 years after they got engaged.

The talk show legend originally agreed to Stedman Graham's proposal in 1992 after six years of dating and he is now planning to ask her a second time, spurred by an emotional trip to South African political figure Nelson Mandela's funeral on December 15.

"It was a highly emotional journey for Oprah, who loved Mandela and everything he stood for. During this time of grief there was only one person in the world she turned to - her Stedman. It was a spiritual mission and Stedman held her close during the funeral service. He realised right then and there he wanted to spend the rest of his life with Oprah as a married couple," a source said.

Friends have been urging motivational speaker Stedman to ask Oprah to marry him again on her 60th birthday, this January. "Stedman feels the two are soul mates, they've lasted together this long and should finally make it official. Stedman also realized that when their days end, he wants to be buried next to Oprah and knows that will only happen if they wed," the source added.