Assalaamu alaykum wa Rahmatullahi wa Barakatuh.
I will start by saying that this is not an anti-polygyny post. Neither is it to put people off polygyny. Rather is it a reality check.
When brothers say they want to show polygyny done properly/well/successfully there is very great danger in those words. Of course, most brothers will say in shaa Allah, but still they are basically saying that they are confident they can do it well. However, they have no idea if they can! For those who have not yet experienced polygyny, everything they plan or imagine is theory, not practice or reality.
There is a danger of arrogance that they think so confidently of themselves when success lies only with Allah. Nobody knows what Allah will test them with, but they are assured that they will be tested with their wealth, their families, their livelihood, their health, etc. This is not exclusive to those whose intention is not Islamically ideal or who go about it in the wrong way. We have endless examples of situations and tests from the early Prophets - alayhim salaat wa salaam - all the way to Prophet Muhammad - sal Allahu alayhi wa sallam. We have examples from our scholars and from everyday life! And yet, even brothers who had failed attempts at marriage, particularly plural marriage, often say they will "get it right the next time."
Subhaan Allah, the selection process is so very critical because they cannot know the heart and mind of the person they marry. They cannot know the reality of the future or how life will be with them until they experience it. All the theory in the world doesn't weigh an ounce compared to real life experience. Perhaps for this reason so many of them fail. The brothers are so sure they have what it takes and Allah shows them His Haqq.
A huge factor in this subject is what I will call the major mismatch. There is a disparity between the type of women who actually want polygyny and the type of women men seeking polygyny want. The sisters who genuinely seek polygyny are usually those who are divorced or widowed, often with children, and unmarried sisters that are older. They need/want the support of a good husband and are not trying to compete or break up an existing family. Often they are considerate of the existing wife and family and will benefit them all.
However, the young, single sisters who agree to polygyny very often have ulterior motives and/or confidence issues. They thrive on the idea that they are better than the existing wife, whether it be younger, thinner, more attractive, or whatever other insecurities they need to feed. Another case is when the younger sisters cannot find suitable single men to marry and settle for polygyny. This results in them feeling dissatisfied with sharing and often leads to them wanting him to divorce the existing wife or any imaginable type of fitnah around their dissatisfaction.
You may ask, how can you say such things Mai? How do you know and how can you judge?
Because I've experienced it personally on a few occasions and seen it on many other occasions. I am not judging; often sisters don't even realize they have these underlying issues and they only surface when they live reality of polygyny. There are always exceptions and may Allah bless all my sisters with what they need. I'm simply sharing thoughts based on years of experience and observations.
Obviously, cultural aspects can play a large part in this and in certain countries and cultures it is normal for young girls to enter into polygyny without such issues. This is often because there is not a strong emotional and communicative relationship in those marriages and the women have a more subservient role, and Allah knows best. I am referring mainly to Western culture, although I have seen this to be rife in Arab culture as well.
So, after all this is taken into consideration and due diligence is done regarding a suitable spouse, pray istikhaara. It it comes back positive and you go ahead and enter into polygyny, just be prepared for tests and if it results in fitnah or divorce, simply accept that Allah led you to it and that test was meant for you.
May all of the Muslims to be rightly guided, have righteous intentions, and succeed in reaching the ultimate goal of Jennah - ameen!
Subhaanak Allahumma wa bihamdika, laa ilaaha ilaa ant, astaghfiruka wa atoobu ilayk.