It is (by a huge huge huge majority) always the man who is older than his wife. The preferred age difference is 3-7 years. I am 3 years older than my wife. My father is 10 years older than my mother and my grandfather is just 6 months older than my grandmother. I have two male friends who have married women 1-2 years older than them. In India, traditional arranged marriages are still the norm (though the trend is changing very rapidly) and these age differences are carefully maintained.