Best way to manage these issues: never tell the SO you have bitcoin. Second best: don't say how much, just some pocket money for the lulz.
These strategies come handy if she ever turns her back on you, too.
Another angle: My wife wants to split, she gets 50%, no regrets and I don't look back. It's all about managing expectations.
It is a good point. if you have 2 units of what ever and count on 1 for her and 1 for you in case of a split its cool.
Or be like me.
My wife earned far more than I ever did from 1986 to 2017.
So I have no worries in a 50-50 split I make out.
Although if BTC keeps whaling away in a few years time I will pass her up in grand total earnings.