Kahlo, a great character and wit who was fluent in four languages, soon developed a cult following for her introspective, retablo-like paintings. She also threw fabulous parties and managed Rivera’s business dealings and accounts. “She ran his life so that he could go out and create, and he opened her to the intellectual jet set of the world,” says Melián.

Yet after her death in 1954, Kahlo’s work fell into obscurity until Hayden Herrera’s 1983 biography Frida helped transform her cultural reputation. (The 2002 movie based on Herrera’s book and starring Salma Hayek brought Kahlo even broader popular recognition.) By the 1990s, her work was reaching the million-dollar range at auction. In May 1995, in Sotheby’s IBM Collection sale, Kahlo overtook her husband’s auction record when her 1942 self-portrait, Autorretrato con chango y loro (“Self-Portrait with Monkey and Parrot”), sold for $3,192,500. She continued to break barriers. Five years later, her 1929 self-portrait in folkloric Tehuana attire achieved $5,065,750, which for a time made her the highest-priced female artist, as well as Latin American artist, at auction. And in May 2006, a 1943 self-portrait, Roots, depicting her floating above a barren landscape with lush green vines growing from her body, sold for $5,616,000—setting another Latin American record that remained until May 2008.

Melián says these prices are due in part to the fact that the work is rare (Kahlo’s total output was around 100 to 150 pictures). but she also believes that the artist’s works sell because “people can relate to her self-examination—i think it speaks to the 20th and 21st centuries.” Kahlo’s great grief in life was her inability to bear children— although they can sometimes impede a career. Anthony Caro’s wife, the painter Sheila Girling, has said that she stopped working in the 1950s while she raised their children. That’s the story for many. Yet motherhood didn’t hold back the sculptor Barbara Hepworth. in 1934 she was living amid the avant-garde of Hampstead, London, with her future husband, the abstract painter Ben Nicholson, when she gave birth to triplets. A month later, she returned to the studio.

“Despite being a young mother, she was extremely keen to pursue her work,” says Philip Harley, a British pictures specialist at Christie’s London. “Consequently, a lot of criticism has come her way for being too focused on her career.” The births provoked a great change in Hepworth’s sculpture, leading to her use of triple elements and groupings and eventually resulting in the monumental pierced forms for which she is now known. Hepworth also suffered from the mistaken assumption that she was a younger follower of the sculptor Henry Moore. They were, in fact, classmates at the Royal College of Art.

Today it seems vastly more possible for art world couples to share power. In many cases, the wife’s career outshines the husband’s (see “Ladies First”). Yet the issue remains loaded. Of the many artists contacted for this story, either directly or through their dealers—including Frankenthaler, Helen Marden, Nancy Rubins, Lisa Yuskavage and the sculptor Sophia Vari, long married to Fernando Botero—most either did not respond or declined to be interviewed. One of the only artists willing to speak on the record was the painter April Gornik, who married another painter, Eric Fischl, in 1998. They have a “figure-ground relationship,” she likes to joke, because while she is known for emotive, luminous landscapes, he paints highly charged figurative scenes.

Their relationship has been going strong since they met at the Nova Scotia College of Art and Design in Halifax in 1975. He was on the faculty and she was a student, but they moved to New York together and their careers took off roughly in tandem in the 1980s, as representational painting resurged. Today the 55-year-old Gornik shows with New York’s Danese Gallery, while her husband has been represented for years by Mary Boone.