The ancient Greeks had six different words (concepts) for “love.” I suspect this statement refers to eros specifically which can feel like insanity because it can override better judgment.

Love or what we call that feeling is a purely biological response to ensure our survival. Firstly we have very vulnerable infants. Newborns would not survive without a caring adult to respond to their needs. This caring response releases endophins and excitatory neurotransmitters. The act of breast feeding release alsorts of positive feelings for the mother. Now as even weaned infants (where most mammals restrict contact with their young) are terribly squishy, so remain involved. These lovely warm positive emotions are delicious and people want to keep having them so they extend the emotional response to other living beings. Consequently we care for babies for as long as they need.

“divine madness” ..I’ll go with that