I think one of the problems when asking these types of questions is that people want a 'standard' or some type of systematized answer that's going to work for all.
The real answer is that it depends on the people involved. I don't believe that age has anything to do with it at all. If two adults truly find love, then discriminating factors such as age, race, or gender should not be factors.
I've been happily married to my wife for a number of years now. I make the most money, I have the final say in the household, and we are madly in love.
She is also 11 years older than I am.