I wasn't thinking of this when I started the poll, but we once discussed the topic about one particular woman. We think she's bi, and we know she cheated on her husband with another man. It would be tempting, but we'd stay away from a threesome. I'd like to think that the fact that her husband is a cop and therefore has ready access to weapons is not the only reason.
The two of them alone was a possibility. Even before swinging she could have sex with any women she wanted to. We don't consider that cheating. However, I'd imagine a lot of couples wouldn't agree with us on that one.
Since swinging, we have discussed it a bit. We just don't think it's fair to the other spouse, and frankly we wouldn't want to be in the middle with any violence, possible court appearances in a divorce, etc.
As to being in love with someone who "found religion" and won't give you sex: people who are in love do get divorced. There's more to a marriage than love. Maybe it's better to be up front about it and mutually divorce rather than get found out, and have them divorce you, get labelled as a cheater and possibly get the shorter end of the stick in the settlement. But I guess that's a personal decision.
People cheat. Flesh is weak and mistakes happen. Alcohol certainly doesn't help. Once you make the decision to go outside of your marriage for sex you've institutionalized it and made it a way of life. It's a big difference.