Sounds like an unpleasant way to live, reminding yourself periodically that you may get dumped by your partner or may feel inclined to dump your partner. I think I'd rather just sharpen the pencil if the worst happened.
Any different than creating a pre-nup and living?
Back when D/W and I married, I don't think the word "prenuptial" had any financial connotation!
Would drawing-down the account as a couple kind of invalidate the fact that it came from one spouse's inheritance and was held in one spouse's name?
In my state, no. It would just be the owner of the separate property spending it as he/she feels fit at that moment.
D/W and I both have our Separate Property account's divs taken as cash and transferred to a common checking account. Which we then use as general revenue. So we are spending the Income, which is
shared property as defined by my state.
But if we wanted to, we either/both could chip off a piece of our own separate property at any time and use it however the owner of the separate property wishes, without imperiling the status of the remaining separate property.
Because both of us invested our separate property in funds that give off dividends (cap gains are reinvested, that is OK here, not a co-mingle), we get income from the separate property while each is alive, and yet the accounts will pass on to our children. If one wanted to absolutely maximize the inheritance to the children, rather than use any of its income ourselves, then it would be best to invest it in something like a growth stock fund, that throws off little/no dividends. But we each decided on our own how we would handle ours. I was first, but D/W could invest hers in anything she wanted, however she wanted.
At first, our kids thought it was a bit strange that they would get something when
either of us dies. But when I explained the concept to them individually, and that, using myself as an example, my relative was leaving it to ME in his will, not D/W & I, they understood. After years of marriage themselves now, they will keep it as their own separate property when they get them. It's sort of like a gold nugget that a relative slips you for your future well-being. It's always yours. And if you never need to cash it in, great, then pass it on to your own children, along with the info of how to handle it.