Just like it is hard for men to tolerate the idea of another man in their woman’s life… its jsut as hard for me to tolerate the idea of another woman in his life. Its not just females that are driven by jealousy… it is men as well. It is HUMAN NATURE to be jealous and has nothing to do with the norms and pressures of society.
Its not just your everyday that you have to share with another woman… its the thought of sharing “a bed” with another woman. Like how can one even fathom the idea your husband being intimate with another woman??? sharing those private moments with another??? like omg ewe.
The whole “lets face it not all guys can control their urges and what if as a wife you can’t keep up with his demands” is a crap reason as well for a man to consider getting another wife. This little mentality goes back to the same “norms and pressures of society shaping one’s thinking” in my opinion. Goes back to the mentality that men are the only sexual creatures and women are there to satisfy them. Um no. Women have urges too and what… just because a man isn’t satisfying them she has the right to go look for it elsewhere??? Um hellz no. And it goes both ways. I doubt the reason why “men can have more than one wife” is allowed in islam is so that “men can satisfy their urges”. Pretty sure it had more to do with the fact that men went off to war more often during that time and there were a ton of widows and children left behind to take care off. This allowance was made to help WOMEN … not the man. And you tell me… today are men taking on second wives that are widows and divorced women with children??? Um no. They are taking second wives for their own pathetic selfish reasons.
Also the whole compulsory “make sure you treat your wives equal” … that is next to impossible. Allah made it difficult on purpose for a man to take on another wife. There is a reason behind this. It is human nature to favor one person over another. Especially in a situation like this.
It’s not about being “entitled to a perfect love story” … its about realizing and understanding that no relationship is perfect and they evolve with time. It is about compromise, understanding, and respect between the married couple.
And if he really wants to help out the world and do it a favor… I am going to say … Lets adopt some children. That is a very noble thing to do and you are truly helping another. Taking on another wife is not “helping another” in todays day and age.
I have heard many stories about men taking on another wife only for the sole reason because they want a son and their wife has only been able to provide them with daughters. That is bakwaas and a cop out.
So yea - in answer to your question: I would have no problem denying him his “right” and would get a divorce if he wanted to go ahead and do this. Its a matter of respect, understanding, and compromise that is lacking if this occurs in my opinion. And that is a recipe for a bad marriage.
Mabey back in the day women were too scared and didn’t have means to support themselves… but the zamana is different. I would have would have more self pride and self-respect for me if I supported myself than having to share a husband 
The same would be said for my family. They wouldn’t let me be “one of the wives” in a million years.