He didn't address couples counseling and therapy as factors in keeping marriages going. There's always been marriage counseling; today it's a professional therapist you hire, but in the old days it was your priest/rabbi/minister, or perhaps an elder in your household, who advised you on how to get along. Today in First World industrial societies, couples just try to wing it, moving out from the parents' house as soon…
That's certainly what evolution has favored (by definition) in terms of primal drives, but that doesn't mean that living life without them is in some sense "empty". Evolution isn't innately wise; e.g. we have very common diseases like cancers, dementia etc in the population because they tend to show up late in life, after the next generation has already been produced. So, just because some particular behavior or attribute is in our genes does not make it "good", it just means that we are programmed in that way due to some set of evolutionary-historical circumstances.
And on the flip side to your point, if you have kids as a way to fill a void in your life, you may find yourself having an existential crisis when they move out and go to college.