It seems to me it is just common sense that it is rude to ask someone so deeply personal a question as why they didn’t receive Communion. It would almost be like asking them what they confessed in Confession.
When it comes to spouses, if the spouse who didn’t receive chooses to share, then that is fine; but the other spouse does not have an absolute right to ask or know. Depending on the relationship between the two, chances are that the spouse knows anyway, especially if it has to do with a habitual sin that one struggles with, such as, say pornography for example. It is more likely to be something like that than some deep dark secret that the spouse is hiding from the other. (If on the other hand it is something like adultery, then that is a different matter; the other spouse does have a right to know about unfaithfulness, but that is still a separate issue than whether he/she has the right to know about an individual instance of abstaining from Communion.) A person’s choice whether or not to receive Communion should never be used as some sort of “what did you do” test.
Hopefully we all agree at least in general that it is rude to ask or speculate about those who do not go forward for the Eucharist, even if we disagree in the case of whether a husband or wife has a right to ask or know.