"Women may attempt to neutralise the masculinity threat of out-earning their partners by reassuring them that they are good sexual performers," the researchers write in the study, published in Social Psychological and Personality Science.
They do this, they say, by faking orgasms.
In the study, around 30 per cent of women earned more than their partners. Data show 27 per cent of women who earned more than their partners faked orgasms, compared with 13 per cent of those who do not.
The effect was amplified when the woman earned "substantially" more, the scientists found.
One in three women (34 per cent) who account for more than 60 per cent of the joint couple income admitted to faking orgasms. The figure was just 14 per cent for women who earn less than 40 per cent.
Lead author Jessica Jordan, of the University of South Florida, said the cause of this phenomenon was complex but stemmed partly from some women being told it was their job to protect men's masculinity in spite of their own unaddressed insecurities.
Academics conducted a further two studies to scrutinise what made a woman more likely to fake orgasm.
"Women are prioritising what they think their partners need over their own sexual needs and satisfaction," said Jordan.
A second study involved data on 283 women and found they felt more anxious and less aroused by men with a precarious sense of masculinity, and this meant their own rate of orgasm plummeted.
A follow-up study on 196 women found that they were more likely to lie about their sexual experience to their partner if they thought he was insecure in his own masculinity.