Islamically the woman has to give permission to her husband to take another wife/wives but this has to be given at the time of HER nikkah, if the first/second etc wife does not agree with her husband taking another wife in the future then she must include this in the nikkah so as to give her the grounds for divorce if he does, i.e breaking of marriage contract. However if she doesnt include this demand that he remain monogomous then he does not need her permission, but also remember that Allah has insisted that a man keep his wife happy so this right to marry more than one wife is only to be exercised when for the greater good & not for selfish reasons, it makes no sense to remarry if this leads to divorce of the first wife, defeats the purpose & hence the first wife must be willing to accept the next wife to keep all involved happy.
Only a woman who holds Islam & her husbands moral integrity highly enough would happily accept another wife. In a perfect world this right would have no place but on this planet where women out number men it is a need to safeguard vulnerable women who need all their needs met & not only financial support.
Everyone can fully understand why a woman would feel cheated on this one but Allah know best, its just a shame that there’s so many men out there who take advantage of this right for the wrong reasons & make their wives suffer for it.
But this right has its logical reasons on this earth & is probably the greatest tests Allah has placed on womenkind. Allah has also tested mankind , we are not naturally monogamous & have strong urges, this is the way Allah has designed man but we are advised to have only one wife aswell as waiting untill we are married etc.
I don’t believe that the majority of men should ever exercise this right as most are weak minded individuals & many are selfish, but there are noble, morally strong men who think of others before themselves & are never selfish who can fullfill the character requirements needed to make this work, their wives would respect their husbands enough to support his decision to remarry as they would be secure in knowing that he was doing it for the right reasons even if they didn’t fully agree…everybodies human.
What we have to remember is that this life is just a test, if Allah has made it halal & if as a woman you believe that your husband is sincere then support him as this will only reward you in the hereafter, if you believe that your husband is doing it for the wrong reasons & is disregarding your feeling then by all means leave him as he is not fullfilling his duties to you & is being selfish & he will be punished for it, but as a human, if you see the good in anything then support it & Allah will reward you, we all need to think much bigger than this world & this life because in the end none of this will matter.
BTW - i only ever intend to marry once, an asprin overdose is nothing to look forward to so 1 woman is enough but if i found myself in the position to help a desperate woman then i would do everything i could to get my wifes support & would proceed only if i had it.
We must strive to please Allah & not ourselves.
Also, women are not only babymaking machines, i would never condone a man remarrying because she couldn’t have children, there are so many orphans out there & adoption is the best path in this case…its a beautiful thing & more of us need to do it.