It's really not a matter of "miscalculating" since all of the numbers are rough estimates anyway.
It's just a matter of being more or less conservative, and those who are less conservative have to have some flexibility incorporated into their plan: either flexible spending, or the ability to generate more income when needed. It's not a failure of the plan, it's part of the plan.
As for going back to work, well, it's a lot easier if you purposely keep your options open, nurture your network, and maintain your skills, which should be a major priority for those with less conservative savings goals.
If you quit, haven't saved enough to weather some uncertainty, have no flexibility in your spending, and do absolutely nothing to sustain your employability...that's not a miscalculation error, that's a lack of common sense error.
Divorce is definitely a big factor, and if your retirement finances absolutely depend on staying together, then it's probably a good idea to sustain some level of employability, just so that you can always be self sufficient.
This is all basic risk analysis stuff, and should be part of any retirement plan, whether retiring early or not.