A guide to teaching English in South Korea states that adultery is not only illegal for the adulterous spouse, but someone who "knowingly had an affair with the adulterous spouse". I'm aware that far more people are charged with adultery than actually jailed, but it still sounds like a good way to ruin a vacation.
For the purposes of a single male visiting South Korea on vacation, what'd constitute "knowingly"? If I've only known the woman briefly, is it sufficient that she's not wearing her wedding ring at the time, or do I need to see her long-form divorce certificate? I assume asking someone if she's married would be somewhat offensive, so I'd only do it if necessary.