I would argue it's after reproduction, successful reproduction that also has successful reproduction even.

Why do grandparents love their grandchildren? Something noble about human nature and love? Or is it evolutionary advantageous?

From my own observations, the relationship retriggers the parenting motivations / dopamine. With the added benefit that you can put the darn thing down at the end of the day and walk away.

From my own observations, the relationship triggers nothing like parenting. There's no feeling of parental obligation, outside of love for that child. So, tell me, why would that evolve in people?

Because old cave-people aren't as good at hunting and gathering, and can be better used as child-care cavepeople.

And survival, and the survival of offspring. Why does menopause exist if evolution is only after sex?

To stop those old, damaged eggs from generating more springs? Perhaps the cell quality decreases as time passes by, and it's better to set those men free to get new ladies, with new eggs.

Why on earth would it be evolutionary beneficial -- if evolution is only after sex -- for a creature to forgo passing on her direct genes in favor of letting another creature pass on hers?