Agree + Stay together ; Agree + Divorce ; Disagree + Stay Together ; Disagree + Divorce
Only one of these has potential risk to the business and it falls under the "Disagree" options. So for the business, agreement is necessary to prevent that risk and some business partners that otherwise might be on board would refuse due to that risk.
Coming into or marrying into money, divorcing for 50%, and "finding a better partner" is not something completely unheard of and it is common enough that people seek protection against it which is why these sort of agreements exist in the first place. If the marriage "isn't about money" then pre/post nups only solidify that fact by putting it into writing: it isn't about the money and won't ever be about the money.
There are two possible perspectives to take here:
A) They would only ask for it in writing if they didn't trust them at their word (people with this perspective will likely side with the wife)
b) They would only refuse to put it in writing if they don't intend to honor their word (people with this perspective will likely side with the husband)