Favoritism breeds jealousy and bitterness, which become the seeds of even greater destruction. To a certain extent, favoritism is inevitable. Parents have favorite children, children have favorite parents, and a polygynous man is almost certain to have a favorite wife. It's just human nature.
That in itself wouldn't be a serious problem except it usually becomes the basis of sin, neglect, or abuse. The firstborn son of a free wife must be considered the firstborn of his father, regardless of how the man feels about that son's mother.
We are prone to poor decisions based on emotion rather than reason and spiritual insight. Torah moderates our weaknesses. If we follow God's laws no matter how we might feel, we are very unlikely to go wrong.
#deuteronomy 22:15-17 #kitetze