Women like bad boys.
This can be scientifically proven, according to Rachel Sussman, a relationship expert currently writing the "The Ultimate Break-up Book for Women."
"Women are naturally attracted to men with the highest testosterone," Sussman told ABCNews.com. "That has been a part of women's DNA since the beginning of time. Women are attracted to very bad, very macho boys, and it might be great sex. But they don't make the best boyfriends -- or the best husbands."
This is a hard fact that Sandra Bullock has spent the past several days internalizing as the news broke that her own bad boy husband, celebrity mechanic Jesse James, may have cheated while she was filming her Oscar-winning role in "The Blind Side."
"Opposites do attract, but they don't necessarily work out in the long term," Sussman said. "Research shows that couples have the best marriages when they have the most things in common and are more similar than different."
Despite that, some opposites attract and even have a very serious and faithful relationship.
Here is a look at five famous couples in which opposites attracted. Two help bolster Sussman's theory, but three are counterintuitively thriving.
On paper it sounded good – the king of pop and the princess of rock-n-roll – but in reality the relationship was a mess.
Twenty days after Lisa Marie Presley's divorce from her first husband, she married Michael Jackson in the Dominican Republic. The pair first met at a Jackson 5 concert when Presley was seven and Jackson was 17. In 1993, they met again through mutual friends and after four months of courting, Jackson proposed over the phone.
The pair began a very public relationship, famously including the famous kiss that Jackson planted on Presley when he opened the 1994 Video Music Awards. Presley also starred in the music video for Jackson's, "You Are Not Alone" wearing only a towel around her waist for most of the video.
The marriage lasted less than two years, but after Jackson's death, Presley wrote on her MySpace page that "Our relationship was not 'a sham' as is being reported in the press. I do believe he loved me as much as he could love anyone and I loved him very much."
One of the world's most famous models and a singer whose face has been scarred by a skin disease? Not exactly a match made in high-fashion heaven.
Nor did the couple get off to the most auspicious start. Seal met Klum just after she had ended a relationship with race car driver Flavor Baritone, and announced that she was pregnant with Baritone's child.
One year after they met, Seal proposed to Klum in an igloo he had built on top of a snowcapped glacier in Vancouver, Canada. When Klum gave birth to her ex's baby, Seal was the one holding her hand through the pushes. Since then the couple has had three children within four years.
The couple have also prospered in their careers. Klum produces and hosts her mega-hit reality show "Project Runway" as Seal has released and toured behind three albums.
'Beniffer,' as the couple was known in their prime, met in 2002 after both had left serious relationships. Affleck dated Gwyneth Paltrow in the late-90's and J Lo had come off a two-year relationship with Sean 'P. Diddy' Combs – it was a classic case of good guy wanting the 'dangerous' bad girl and the bad girl trying to clean up her act.