Adapted from a recent online discussion.

Question: I cheated on my spouse. One night. With a friend who is also married. We both have happy marriages and happy families and love our spouses and our children dearly. Neither of us has any interest in blowing up our lives. We just happened to be out of town in the same place and wound up finding each other irresistible, for that one night. We don't live in the same state.

I know how people feel about infidelity. But, honestly, I'm starting to wonder if this kind of thing isn't much more common than we think. Is this something you hear a lot? It happened, things happen, it was nice, no plans to do it again, no reason to hurt my spouse and destroy our lives, life goes on? Or am I possibly evil and don't realize it?

Answer: There has long been an oh-come-on disconnect between how harshly people judge infidelity and how frequently people indulge in it. So, I can agree with you that it's probably much more common than people think - but I also don't like the sensation I have right now of being used to normalize your choice to do something that could be devastating to your spouses and, by extension, to your kids.

And because this is a complicated topic, I feel the need to say that I also don't want my words to be weaponized by those who regard infidelity as a crime against everything that matters.

Here's what I think about it in general and about what you did specifically: People are best paired with those who share their views of infidelity, whether they're strict in holding a fidelity-or-divorce line or are full-on French about having lovers. People need to think about this carefully, and couples need to talk about this early. Infidelity is often impulsive, but our understanding of it and reactions to it shouldn't be.

If you'd be fine with your husband having a tryst of opportunity himself, and if you have reasonable confidence he's about where you are on this philosophically, let someone else sit in judgment. I won't.

If, instead, there are lies of wishful thinking here, your conscience needs to reckon with those.

This might be where you expect to see a "tell him" or "don't tell him" suggestion, but, my apologies, you're not going to get one. It's too dependent both on what the would-be recipient of the bad news would want, and on how you respond emotionally to carrying your secret. Telling could gratuitously injure someone, and not telling could do the same, and the person in the best position to distinguish between the two is the cheater, so he or she is on the hook to make that call unselfishly. Heavy stuff. Arguably, that's deterrent enough for future trysts of opportunity.

Couples who missed their chance to explore this topic early and who find themselves poorly matched in their views face a tough choice of their own. My suggestion: When the topic comes up organically - as it inevitably does, over a neighbor or friend or celeb - be honest about where you differ and why and about what it'll take for you both to agree to disagree.

Chat with Carolyn Hax online at noon Fridays at www.washingtonpost.com.