I believe there is a difference between a drunken one night stand and a full blown secret affair that last for years. I know that unhappy wifes are easy targets.
Personal tolerances. For me, monogamy is a core promise, so cheating is unacceptable. Drunken one-night stands typically require choosing to have drinks under questionable circumstances. I've been the OM more than once, where it was clear to me the spouse was angling for an "oops" moment. I drew a line the one time my partner tried to be intimate after going to a bar and "forgetting" the evening. It jogged her memory.
