Time was when a roof over your head, food on the table and occasional bouts of sexual activity were the hallmarks of a successful marriage. Not any more. According to a US psychologist, the modern marriage must fulfil far deeper demands, and most couples are struggling to cope.

Eli Finkel, director of social psychology at Northwestern University in Illinois, said couples today looked to their marriages to help them "grow as individuals", and support them through "voyages of self-discovery". But their expectations are rarely met, he said, because of the investment of time and effort involved.

Finkel claims that persistent high divorce rates and low levels of marital satisfaction are a direct result of couples being unable to meet the psychological expectations of their partners. While overall demands on marriages have not changed much over time, he said, the nature of the demands has shifted and they require more time and effort to satisfy.

"In the past, you married someone who helped you meet your basic needs, but over time, love increasingly conquered marriage. Now people are looking to their spouses to help them discover who they are, and to achieve the best version of themselves," Finkel said.

Speaking at the American Association for the Advancement of Science annual meeting in Chicago, Finkel said that most couples struggle because the change in demands calls for more investment in marriage in an age when many people have less time on their hands.

"People used to marry for basic things like food and shelter. In the 1800s, you didn't have to have profound insight into your partner's core essence to tend to the chickens or build a sound physical structure against the snow," Finkel said. "Back then, the idea of marrying for love was ludicrous."

"In 2014, you are really hoping that your partner can help you on a voyage of discovery and personal growth, but your partner cannot do that unless he or she really knows who you are, and really understands your core essence. That requires much greater investment of time and psychological resources," he said.

A blissful minority are in marriages that fulfil these deeper demands, and those marriages are better than the best marriages of yesteryear, Finkel claims. But the average marriage falls short because the time and effort required were impossible for most to meet.

Finkel arrived at his theory – which has not met with universal approval – after reviewing studies on the psychology, history and sociology of marriage. He said marriage had gone through a series of distinct transitions as countries and individuals grew wealthier and cultural transformations played out. Since the 1850s, marriage had become less about basic needs and more about love and companionship.

In the 1960s, love and companionship remained central to marriage, but these were joined by other factors, including the personal growth of the couple. In modern marriages, people look to their partners "to help them find themselves, and to pursue careers and other activities that facilitate the expression of their core self", he said.

Despite naming his theory the "suffocation model of marriage", Finkel maintains he is optimistic about the institution. He said couples could improve the quality of their marriages by allowing them to breathe, for example by lowering their demands on the relationship in hard times, such as when the couple had young children or faced work or money problems. "Some people will realise they are asking a lot of their marriage given the 30 minutes a week they spend talking to their wife," he said. "The irony is that asking less of the marriage when resources are scarce will actually make the marriage stronger."

Lynne Jamieson, who studies the sociology of families and relationships at Edinburgh University, said that the demands on marriages vary hugely over time and between people from different social and economic backgrounds. "The argument that we now spend less time on relationships is not so clearcut," she said.

Scores of factors come into play. While couples tended to have more children in the past, she said, more households now have two working parents. Both are a demand on time. People today live longer, which also adds to the pressure in marriages. In the past, more families would lose a parent while children were still growing up.

Having a deeper understanding of each other might not be the whole story, Jamieson suggested. "Making somebody a cup of tea as a gesture, especially first thing in morning, is very important to people. Those little gestures can be as important as profound conversation," she said. "Sometimes actions do speak louder than words."