I gotta say, when I started reading this, I was pretty dubious.

I can see how a 2 of 2 could align incentives. A couple has to work together to maintain access to their funds. But it sure feels like fixing the wrong problem. If a couples' funds or the way they store them are an issue, that isn't the issue.

If marriage isn't based on a commitment between two people, what even are you doing? It might be simpler just to put the time into building the relationship, instead of the multisig.