In the age of hookups, friends with benefits and online dating, and as human life expectancy grows, is it still reasonable to expect people to pair up and stay monogamous until death do them part?
"It's realistic that some people can mate for life in the same sense that some people can play the Beethoven violin concerto or other people can ice-skate beautifully or learn a new language," said psychiatrist Judith Eve Lipton.
Added evolutionary biologist David Barash, "It's within the realm of human potential, but it's not easy."
Lipton and Barash, who have been married 32 years and are the co-authors of "Strange Bedfellows" and "The Myth of Monogamy," said serial monogamy may be more realistic -- a model in which people move from one committed long-term relationship to another and choose partners for different reasons at different stages of their life.
Possibilities in polyamory?
For some, even serial monogamy seems too restrictive.
The 1970s introduced the concept of "open marriage" in which couples stayed married but were free to date other people.
More recently, polyamory -- the practice of having romantic relationships with multiple people at the same time with the full knowledge and consent of all involved -- has been getting a lot of attention.
"We found the expectation that one person should be our everything seemed unrealistic given our day and age. ... It's oddly pressuring to set up that scenario," said Mark, who lives in Springfield, Missouri, and is in a polyamorous relationship. (He asked that his last name not be used for privacy reasons.)
Mark, 42, has been married for five years. He and his wife tried different things to spice up their marriage, including swinging, or having casual sex with other people, he said. But they found the experience unfulfilling and decided what they really wanted was to be able to fall in love with others while staying together.