It gets very complicated. In my case my current partner had assets of her own when we cohabited. So ours reads as you have suggested and she cannot touch my assets or their growth nor I hers and they are listed clearly including my business interests.
I hope my agreement stands up but when it comes to a spouse in Ontario Family Law is field day for lawyers.
And yes, a non mentally debilitating terminal disease with 3 years to live would be perfect....I'd dump everything and then get on a plane first class to Switzerland long before the end!