Single-Women-Who-Date-Men, I think we really only have to remember two things, preferably BEFORE the first date begins:
1. Ask him, "Have you ever been married?"
2. If the answer is yes, ask him, "Are you married right now?"
Do not date a married man. Don't do it even if he's the most wonderful guy you've met in years, even if he swears his marriage is over, even if his wife has lived in another state or country for years. Do not date a married man. Just don't.
Oh, all right. If you have to do it just to learn the lesson, go ahead.