The likelihood of going back to what we had is very small IMO. People would lose their minds. That aside, I doubt what could possibly happen informed her decision to stay or go or her feelings about it.
However, as to wanting to stay in a dead marriage due to health insurance coverage in general, and worrying about the costs, yes it certainly happens in our country. And she could've been concerned about it.
But she could qualify for Medicaid. Even if he had health insurance available. It covers single parents and their children regardless of whether another parent has coverage.
It's more often spouses who don't have kids that I see worry about staying married so they won't lose their benefits. I don't see it as much with parents.
And apparently the Colorado ACA is as comprehensive as in CA. Even for people who are middle class earners. Like CA they have their own, health care exchange and it offers pretty low rates to people depending on their situation.
Yes, she would be entitled to COBRA. And to transitioning to the ACA via her current plan. Which is likely what she would do instead.