In concept something like the assets or split of the assets you have entering the marriage with should be the assets or split of the assets after the marriage but The value growth of those assets and benefits created during the time of the marriage split equally. If either one of you is skipping an opportunity to build their own assets to contribute to the marriage that should be reflected or agreed to be evaluated at the conclusion. Potentially with a cash flow or a different split of the assets.

If the prenup were defined as your business assets are 100% yours after the divorce, and all your efforts during the marriage go into growing the value of that asset and all her efforts go into home maintenance and childcare etc, freeing you to devote fully to building your assets, and then at the end there is no consideration of her contribution to your business assets growth then I would say that’s fucked up.

In the event of the divorce custody of the children would need to be another consideration. A cash flow would need to follow the children’s custody. If she ends up with 100% custody you need to continue covering the costs of the needs of your children. 

I would error on the side of your future wife being better off than what you think a strictly fair distribution would be.    The sacrafices, assets and capital she will be building for your union in this scenario will not exist on a ledger but are real and should be accounted for.

I’m not a lawyer. You asked for random opinions from strangers on the internet.