You have arrived at this link because you were really paying attention.  I have made this hard to find because I think you will find this page is particularly controversial.  Let me start with a few realities not mentioned in the Assumptions page.

Older women tend to like sex more than younger women.  Perhaps this may be because of genetic programming over the history of humankind.  If a woman has lived to the age of 30 plus, she is probably in a situation that is more likely to have proved stable.  She will be more experienced and better able to fend for her family if the man leaves, so nature rewards her with a stronger drive to have children.

Older men tend to want to have sex with younger women, who in turn are more open minded about whom they will have sex with on a longer term basis.  The older men may see the younger women as more in love with them, when perhaps they are just not as set in their ways, they may not know themselves and what they want as much as when they get older, they may look up to the experience that comes with age, or find that older men who have had the time to be successful in life have actually done so and so are more likely to be able to provide a materially and socially stable environment in which to raise a family.

Relationships need love and yet space, respect and yet playfulness, consistency and yet change.  Without a balance of these relationships go stale.

If people who are similar tend to bond, it would follow that really smart, handsome people will seek the same.  But on the other end of the spectrum, the not so smart and the not so handsome perhaps might seek other not so smart or not so handsome people so that they are on the same social level and not as likely to be abandoned.  However, secretly, they might actually have chosen a smart or handsome mate had they had some way of achieving the smar/handsome intended mate's attention and affection, and not been afraid of losing that person when a better alternative came along.  The children of the best people will most likely have the same high characteristics, and if the people on the other end have children by each other, the children may well tend to be not so smart or not so handsome.

Besides genetic engineering, which is not yet a reality, we could look at how to match "mentor" type relationships where a smart and handsome person might choose a like mate and also accept a not so smart, not so handsome mate.  This is not an edict.  It is a goofy idea to spark thought and discussion about how to give the "have nots" a chance to be part of the best.  The children of the not so smart, not so handsome would be much more likely to have smarter and more handsome characteristics.  It has been happening de facto for a while if you consider how many men throughout history have taken mistresses while married, and how many women have actually borne children not fathered by their husbands.

Hypothesis: A social benefit of monagamy is that younger women, driven by a different set of hormones than younger men, are better able to keep a clear head and choose mates who will be successful.  (Alcohol is a demonstrated override of this.)  If younger men are not successful, they can become so with effort, and thus become more desirable mates, although even then there is no guarantee they will actually entice a mate.

As people become older, they accumulate a progressively deeper and more accurate understanding of themselves.  Along with this comes a lowering of tolerance for things that conflict with their increasing selfawareness.

Divorce is statistically more likely in families where resources (e.g. money) are inadequate.

Physical intimacy tends to create an affectionate bond.  If this contradicts one or the other's opinion of their mate, the situation can become explosive if they are required to remain together.  Do we need to return to "pruder" times?