Americans are increasingly cheating on partners, are more open to multiple lovers, and less keen on monogamy, a new survey on changing attitudes to sex and love has revealed.

YouGov polling this month shows that while most Americans still want a wholly monogamous marriage, the numbers are slipping as people increasingly accept some degree of dallying.

Meanwhile, polygamy — the custom of having more than one spouse at the same time — remains mostly taboo, but nearly a fifth of US adults say it will be legal within 50 years.