A new study says that boys taught in single-sex schools are more likely to be divorced or separated from their partner than those who attended a mixed school by their early 40s.
The research, by London's Institute of Education, added that those who stayed together were just as likely to be happy in their relationship as men educated in mixed schools - when asked to rate the quality of their marriage on a scale of one to seven.
To reach the conclusion, researchers studied a cohort of all those born in a single week of 1958, reports The Independent.
The findings will be presented by Professor Diana Leonard, from London University's Institute of Education, at a conference at the Perse School for Girls in Cambridge.
The research covered 17,000 adults who had been taught in a range of institutions from private boarding schools to state comprehensives. The majority had been brought up in day schools.
Mary Bousted, general secretary of the Association of Teachers and Lecturers, said: "All the research shows single-sex schools are good for girls but bad for boys - both in terms of academic performance and socialisation.
"Girls seem to learn what the nature of the beast is if they have been to single sex schools whereas boys taught on their own seem to find girls more puzzling."
Bousted added: "Boys learn better when they are with girls and they actually learn to get on better."