From the Wisdom Surrounding Taking Multiple Wives
So the existence of jealousy in us is only natural, thus it is obligatory that we are patient. Patience is from the fruits of having faith in Qadr (Divine Pre-ordainment) as mentioned by my father and my Shaykh in his book,  and all of the actions of Allaah the Mighty and Majestic are wise. However, this wisdom may or may not become apparent.
From the wisdom surrounding taking multiple wives: