Middle-aged men are more likely to have a poor sex life if their wife is too close to his friends because it undermines their masculinity, a new study has claimed.
According to the study, conducted by researchers from Cornell University, "partner betweenness" undermines men's feelings of autonomy and privacy, which are central to traditional concepts of masculinity.
"Partner betweeness" means that a romantic partner comes between a man and his friends.
"Men who experience partner betweenness in their joint relationships are more likely to have trouble getting or maintaining an erection and are also more likely to experience difficulty achieving orgasm during sex," the Telegraph quoted Benjamin Cornwell, the study6 leader as saying.
"There is a bit of a gate-keeper aspect that probably troubles some men," he said.
They found that partner betweenness can in turn lead to overt conflict or problems with partner satisfaction and attraction.
The researchers said that there was nothing wrong with the wife organising most of their social activities because females tended to be more organised.
However, they added that reducing a man's contact with his friends to the point that a couple only socialised together was not healthy, suggesting that so called "boys nights" could, in fact, be a good thing.
"They key issue is whether it reduces his contact with his friends while it increases hers, for example she alters his social schedule to the point that his contact with his friends increasingly occurs in the context of couple's dinners," Cornwell said.
"A man's ability to play a round of golf or to have a few drinks with a friend who has only a passing acquaintance to his wife or girlfriend is crucial to preserving some independence in everyday life.
"If he has to bring his wife along every time they meet, or his wife starts monopolising that friend, that's when problems may arise," he said.
The team used data from more than 3000 people aged 57 to 85 to make their findings.
"The results point to the importance of social network factors that are rarely considered in medical research - network structure and the individual'[s position within it," Edward Laumann from the University of Chicago, who was also involved in the study, said.
"He needs to have someone to talk to about the things that matter to him, whether its football, politics, what car he is going to buy or worries about his health or his job.
"The important thing is that he can let it all hang out and know that what he says isn't going to get straight back to his wife," he said.
The researchers analysed data from the 2005 National Social Life, Health and Aging Project, undertaken in Chicago.
They concluded that the social networks shared by men and their female partners could have a link to erectile dysfunction.
The study has been published in the American Journal Of Sociology