Couples should not worry when the first flush of passion dims – scientists have identified the hormone changes which cause the switch from lust to cuddles.
A team from the University of Pisa in Italy found the bodily chemistry which makes people sexually attractive to new partners lasts, at most, two years.
When couples move into a “stable relationship” phase, other hormones take over, Chemistry World reports.
But one psychologist warned the hormone shift is wrongly seen as negative.
Dr Petra Boynton, of the British Psychological Society, said there was a danger people might feel they should take hormone supplements to make them feel the initial rush of lust once more.
See also the work of Helen Fisher.