Salaam,
As there will be differing views on marrying more than one wife depending on a persons own standpoint, I have a solution for those women who would be absolutely opposed to the idea of their husband taking another wife and they should do it before entering marriage.
Apart from discussing the issue with her future husband, she should make it clear in the marriage contract that she has a right to request that during their marriage he agrees not to marry another woman.
The marriage contract is surprisingly overlooked amongst Muslims, who could save a lot of heartache later on in their lives, if only they discussed their viewpoint openly. That is why it is called a contract.