To clarify: My father is 21 years older than my mother... and his oldest daughter is 7 years younger than my mother, this maybe why my sister dislikes my mother:P But i think that since my mother was 35 the age gap ceases to be so important after a certain point but there is a limit.
An example of that limit: the prophet Muhammad married Aisha when she was 9 and he was in his 50's, there is speculation that the Sunni/Shia divide was exacerbated by the fact that Fatima was slightly older than her step mother and therefore didn't like her. This age gap is too great, especially since the wife was playing with her dolls...
Having said all that actually I do disapprove of women marrying younger men... I know that sounds sexist, but it is really biological, women cease to be fertile at menopause and start to age rapidly after that, also women seek alpha males and lose respect for men who they support (a study was done that showed that women who had house husbands lost interest in their husbands when natural gender roles were reversed.
