"On Feb. 2, 1961, several months after they met, Obama's parents got married in Maui, according to divorce records. It was a Thursday. At that point, Ann was three months pregnant with Barack Obama II. Friends did not learn of the wedding until afterward. "Nobody was invited," says Abercrombie. The motivations behind the marriage remain a mystery, even to Obama. "I never probed my mother about the details. Did they decide to get married because she was already pregnant? Or did he propose to her in the traditional, formal way?" Obama wonders. "I suppose, had she not passed away, I would have asked more.""
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..."Ann filed for divorce in Honolulu in January 1964, citing "grievous mental suffering"—the reason given in most divorces at the time. Obama Sr. signed for the papers in Cambridge, Mass., and did not contest the divorce."
http://www.time.com/time/printout/0,8816,1729524,00.html
And no friends witnessed the Obama/Dunham marriage according to the friend reported by Time mag above.
Thanks.