People Magazine reported Sunday that, according to Twain's representative, the ceremony took place at sunset on New Year's Day at Rincon in Puerto Rico with about 40 family and friends in attendance.
Twain and Thiebaud met in 2009 and, according to People, clicked due in part to the fact that both of their previous marriages had ended due to unfaithful spouses.
People said Twain wrote in a Web site statement last month that Thiebaud was "a true gift to me as a compassionate friend."
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