Why would women shy away from a prenup?

I have two buddies who are considering marriage.
The girls are great by the way and, until this glitch, I thought they had chosen potentially good partners.
But in both case, the guys want a prenup (and I can’t discount the possibility that my own divorce has inspired this strategy)
Both, like me, are well past their 20’s and have careers and property. The terms are very reasonable. Their current property is exempted from division if divorce occurs.
In the event of divorce, their spousal support and division is calculated by what the girl contributed during the marriage, with all sorts of provisions about raising small children etc.
Child support would be according to statute.
Nothing crazy, just an agreement regarding the contribution of each partner to the community assets.
In both case, the girls are resisting.
They wonder if they are being unreasonable.
I say, (not to their faces, by the way) the women don’t want to give up a freebie since in our state they get half of everything, whether they contributed anything or not.
What do you say?