Natural Selection doesn't care if any individual is happy with its situation. All that matters is if the individual manages to reproduce successfully.
Miserable people having miserable children who go on to produce more miserable children. As long as you don't get so miserable that there isn't some miserable person out there willing to bang you and create more miserable people despite the misery, your suffering doesn't rate a second glance.
Evolution gets it right enough. It's the universe saying, "Meh", and going back to bed.

FTFY