Woman prefers to stay alone for exchange of assurance... Man risks his wife for loneliness for exchange of respect...

I think most of us are somewhat agree that woman tends to look for older man to be her husband.

(1) Older man is associated with more mature characters, more stable financially, etc. Woman wants assurance of anything. ^_^

(2) A study by UN said that female has longer life expectancy compared to its of male by 4 years.
That means to be able to maximize the time spent together (couple), the female must be 4 years older than the male at the time of dating or of marriage. So the couple will meet and die at the same year. No one is left behind. Time spent is maximized, and both parties are happy. Example :
- The male will die at age of 76, and The female will die at age of 80. If they meet each other when the male is 21 and the female is 20. That means after 55 years, the male will die, and by the time, the female is 75 years only. She still has last 5 years to live alone.
- Another example, if they meet each other when the male is 21 years old and the female is 25 years old. That means after 55 years, both of them will die. No one is left behind.
You can try any different numbers, with different age difference.

(3) The only optimal solution is the male should be 4 years younger than the female (objective : maximum time spent together, none of them is left behind).

Knowing the fact (3), woman still choose older man. It implies that maturity and financial assurance is more important than time spent together, in woman's eye.

Probably, woman does not really care of maximizing their time spent with their husband. They want assurance emotionally and financially. They risks themselves of staying alone for several years after the death of her husband.

The story does not end here. It is a two side of coin.

Now, let's see for the male side. Man tends to look for younger woman. Probably, man likes the kind of respect they can get from younger woman. If it is the only thing man considers, respect is the most important factor among other things. Man risks his wife of staying alone for several years in exchange of respect.

Above analysis is, by all means, not exhaustive. I just try to offer a narrow view of man and woman relationship, which is probably true to some extent.