The answer is: she is not divorced, because it was based on a cause that was shown not to exist. This is the correct analogy, both legally and factually.

Issue: If a fasting man forgetfully eats until only a small amount of food remains, and then eats it on the interpretation that, if what he previously ate forgetfully did not invalidate his fast despite being a larger amount, then the smaller amount likewise does not invalidate it as a consequence; whereas if what he previously ate did invalidate the fast, then he is no longer fasting and may eat the remainder—would he be excused for this? According to the established position of the madhhab, ignorance is not an excuse, so he would not be excused in this case. According to the stronger view—that ignorance is excused—there are two possibilities: he may be excused because of his interpretation, or he may not be excused due to his negligence, since in this case he was obliged to ask. In any event, making up the fast is more cautious. And Allah knows best.

“Or a fly or dust enters his throat …”

His statement, “Or a fly or dust enters his throat,” means that his fast is not invalidated, because this occurred unintentionally. However, if it flies into the farthest part of the mouth, he can remove it; it is only when it reaches the throat that he cannot remove it. Indeed, if he attempts to remove it, he may vomit. He is therefore excused for it. Likewise, if dust enters his throat, his fast is not invalidated, because it was unintentional. Nor should a laborer who works with soil be told: “Do not work while fasting, because if you work while fasting, dust will enter your throat.” For we say: dust entering his throat is not intentional. But might it not be said: since this work is a cause of his breaking the fast, he must not work?

The answer is: this is not a cause of his breaking the fast, because if dust enters his throat unintentionally, his fast is not invalidated.