To clarify, my comment was not about what is a reasonable assumption given the current legal state of affairs. It was a suggestion for how married couples could legally be viewed.
In practice, I would guess that most people who sign NDAs and are married just disregard them when it comes to one's spouse, so people providing NDAs really should be aware of that if they're concerned.
Recently, LWers Will Ryan and Divia Melwani (now Will and Divia Eden) were married, with Eliezer Yudkowsky officiating.
I've been to 40+ weddings in my lifetime, and this was my favorite ceremony yet. Here is the video, and below is the transcript of Eliezer's... what's it called? "Blessing"?