It is not a simple question to answer simply because there is no answer. It all depends on the spouse's character, the nature of the relationship and the eventual money problems that may develop as result of starting a new business.

The spouse is a furious entrepreneur? The spouse will jump at the opportunity and will be part of every aspect of this new adventure! But, how often does that happen?

You have great financing behind (from investors or your own money), you draw a reasonably fat salary check every month so, what's the difference? But, how often does that happen?

The spouse has a great job with a salary more than enough to cover for a comfortable life style. The spouse is also willing to support the initiative for a certain period of time. You know you will be fine at least for a while. This happens more often but still...

Then we have a spouse that is not and entrepreneur, you depend on the revenue of the startup to make a living, you have no money and no deep pocket investors and the spouse has a modest job or no job at all? Be ready for the worse. Love can only take so much pounding!