My BF is really fighting for his share of assets from the marriage and she was obviously planning to keep some extra since seh changed jobs a year before her affair was discovered and was putting a disproportionately large sum into the new job's 401k. She wants to split the other accounts 50/50 but sort of left that out one and doesn't want to split it.
And I really had to fight my way up financially after being left in ruins from my divorce, so I would be OK if we signed something that documented our assets on the date of marriage and anything after that was up to equitable distribution in the event of a divorce. I just really wouldn't want to be left with nothing and if that made him feel better, I would. I don't see it as a precursor to divorce, rather a reassurance that I'm in it for him, not his assets (which are more than mine).