Living separately or allowing your partner to sleep with other people could be the key to a successful marriage, psychologists at one US university have claimed.
They argue that "outsourcing" areas of marriage to other people could save relationships in the long term.
This is because people are expecting more from a partner than ever before.
Couples are not only looking for a lover and a friend, but someone who also inspires them creatively and can help them achieve their long-term career and personal goals.
Eli Finkel, of the department of psychology at Northwestern University in Illinois, advises embarking upon an agreed "non-monogamous" relationship if couples no longer feel sexually attracted to each other.
Living apart could also revive some of the mystique of courtship and relieve monotony, he claims.
"It may be that your spouse is a terrific source of social support and intellectual stimulation but you haven't had sex more than twice a year for the last five years and neither of you thinks that's adequate," he said.
"So you could say, that's one of the needs I am going to fulfil elsewhere. I don't recommend cheating, but an openly consensual non-monogamous relationship, that may very well be functional."
In a paper entitled 'Suffocation of Marriage', Prof Finkel argues that problems have arisen because marriage is no longer about meeting basic survival needs. "In 1800 you didn't have to have a profound insight into your partner's core essence to tend the chickens properly or build a sound physical structure out of the snow," he said.
"In contrast, in 2014 you are really hoping your partner can help you on your voyage of self discovery and personal growth.
"We are looking less and less to our marriage to fulfil our basic psychological needs, but more and more to our marriage to fulfil these higher needs like self-expression and self-actualisation. So what you are seeing is a splitting in marital quality such that the best marriages are spectacularly good but the average marriage is getting worse over time."
Prof Finkel presented his research at the annual conference of the American Association for the Advancement of Science in Chicago. (© Daily Telegraph, London)