Women get bored of having sex with their partner after just a year together, a new study suggests.
They are four times more likely to not care about having a steamy night of passion than those in shorter relationships.
But the same trend does not exist for men. Their sexual interest does not fade over time, researchers claim.
The 'important' findings, made by Southampton University researchers, were based on answers from 11,508 participants.
Women who have been in relationships for longer than a year are four times more likely to not care about having a steamy night of passion than those in shorter flings
The National Survey of Sexual Attitudes and Lifestyles is the largest study of sexual habits in the UK. This was the third one undertaken.
What else did the study find?
Overall, 34 per cent of women said they lacked interest in sex, compared with 15 per cent of men, the study published in BMJ Open found.
The survey showed that both men and women were at risk of being put off sex by past experiences of forced sex.
Other passion-killers included poor mental and physical health or having recently had a sexually transmitted infection.
For women, having had three or more partners in a year was linked to a decline in libido alongside having children under five.
Having sex at least once a week slows aging in women - even if they do not enjoy being intimate, research found in July.
Being active between the sheets increases the length of women's telomeres, University of