Two mutually exclusive issues happen: women are raised to be beautiful and are encouraged to achieve "good" marriages (euphemism for the wealthy) since they are small, and it has been done for hundreds of years (read Pride and Prejudice).
At the same time, men are urged to get a "good name" (euphemism for "fortune"), but not as much as they are encouraged to marry. It is not as bad seen in western society to be a "bachelor" as an "old maid"; in the end ... the marriage of a man can wait, that of a woman not (he must marry in the heyday of his fertile life, after 20 he considered himself an "old maid" that would be a burden for his parents.
Now, is it that nobody thinks that these two behaviors are mutually exclusive? Men spend their lives accumulating wealth, but the woman must marry quickly, for this reason, the age difference used to be large (unless of course, the man was a young heir).
On the other hand, beautiful women (of whatever social class) are raining proposals. I dare say that the more beautiful (without daring to make moral judgments about whether they are educated or not, whether they are educated or not, whether they work or not), they receive many more proposals, so they quickly learn to ponder. Not a system that they implanted, but a system that encouraged them to accept the proposal of the luckiest suitor.
Consequently, girls who are not perceived as "as beautiful" as the former, socially, used to be single. But this was from Victorian England.
The more society advances, the more women are educated (whether they are perceived as beautiful or not), among men they are more open to look for other qualities and not just the physical one, (of course some bipartite sexual attraction will always be important), more these criteria are abandoned, and the freer the women are, the more freedom they will choose their spouses, whether they are lucky (or not).
Middle aged woman can't be attractive ????????