First off let me state that I am not a Christian nor am I by far an expert in Christian Theology. I know what I heaver learned I Sunday School, and a lifetime of fascination with humanity and its religion in general. However, snark aside, I don’t see where my reasoning if wrong.
In God’s glorious and perfection heaven, this is no evil and nothing can be wrong. For those who are saved, and therefore absolved of their earthly sins, heaven is a timeless infinity in the presence of your loved one, provided that they were also saved, and God’s eternal, merciful, and loving spirit,
Love is God’s greatest gift, and it is not only expected but required that we love one another, but the love of spouse is an elevated love, it is a love created by the special bonds that ties you to another person for life. It is expressed by a commitment to that person, and that person alone, forsaking all others. In the traditional Christian view, marriage is a lifetime vow, broken only by death.
Death does however break it, and those who have tragically lost their spouse are not excluded from the matrimonial love, but are allowed to marry again, recommitting their vows ‘until death do them part.’ The dangers of childbirth, no greatly reduced by modern medicine and clean hands, robbed many a family of their mother and many a man of his wife, creating the need for the second wife, the step-mother.
In heaven you are reunited with your loved who preceded you into God’s graces. That means you must be reunited with your previous spouses, whom you did love unto death, and you will be joined by the spouses you left behind when you passed away. In heaven many will live forever in perfect harmonious polyamarous relationships. What is good in heaven cannot be evil on earth. Evil and wrongness have no place in God’s grace, therefore poly relationships built upon love and respect can only mirror God’s will for the afterlife of the just and cannot be considered immoral , unnatural, or sinful, but only a proper expression of his divine plan on earth as it is in heaven.
For the record I am not poly either, but the logic still seems watertight to me.