You might think a man's life would be made that little bit easier if his wife gets on well with his pals. But while it might be good for the social life, it could spell disaster in the bedroom。
Middle-aged men whose partners get on very well with their own friends can suffer a severe loss of sex drive, a study claims。
Scientists say that even though these relationships are normally completely harmless, they can have a negative effect on the husband's feelings of power and masculinity。
The researchers looked at the health records and details of social activities of 3,000 men aged between 57 and 85. They found that men who reported problems in their sex lives were much more likely to have the same circle of friends as their wife。
The scientists, from the Universities of Chicago and Cornell, in New York, have labelled the problem "partner betweenness"。
Writing in the American Journal of Sociology, the authors said: "In such cases, a man's female partner has stronger relationships with his confidants than the man does, which can lead to him losing his self-esteem and sexual desire."
"In effect, partner betweenness undermines men's feelings of autonomy and privacy, which are central to traditional concepts of masculinity. This can lead to overt conflict or problems with partner satisfaction and attraction."
Separate figures show that as many as one in five men have a low sex drive, which is often caused by age, illness, certain medications or even lack of sleep。
In some cases a low sex drive can be a sign of a more serious health problem, such as heart disease or diabetes, and experts believe that a husband or wife's low libido is one of the main reasons why marriages break down。