Married couples have sex 58 times on average each year, or a little more than once a week. However, those under age 30 have sex about 111 times a year, while 15 per cent of married couples haven’t had sex with each other in the last six months to a year. In an interview with the New York Times, Denise A. Donnelly, associate professor of sociology at Georgia State University, says some marriages are always sexless, while in others, the sex fades away. Sometimes people become bored of their spouse, or the demands of having a family and career sap their energy. Some people have low sex drives, and then lose interest. Couples in sexless marriages are generally less happy than those having sex, she reports; the more sex a couple has, the happier they report being.