There is no evidence that anything other than wide age differences increase the likelihood of splitting up – more than 10 years, and the younger partner is more likely to be unhappy than in more standard relationships. Typically, relationships with wider age gaps are more prevalent among poorer, less well-educated couples, and in certain ethnic communities. Couples who differ widely in age are also more likely to cohabit than marry. There's no evidence they have less to talk about, and as for friends, a partner's mates are never as interesting as yours, whatever their ages.