Camilla, Duchess of Cornwall
An on-again, off-again relationship gets a little more attention when it's with Britain's Prince Charles — and especially when one of those "on" periods was during his marriage to Princess Diana. Lurid (and bizarre) conversations between the two were leaked in 1993, which didn't help Camilla's cause. Married at the time as well, she kept a low profile in the press but eventually divorced her husband and married her suitor after Princess Di perished in a tragic car accident.
Post-affair: The pair had a low-key wedding (by royal standards) in 2005, and the royal family has gradually accepted Camilla into its ranks. Though she could have opted for the title "Princess of Wales" like Diana's, Camilla chose to become the Duchess of Cornwall instead. She has been lauded for her charity efforts on the royal family's behalf.