Life is all about gray areas, and people cheat for all sorts of reasons. I'm more inclined to forgive someone for cheating before marriage, when there's no real "contract," than after, once finances have been mixed and the possibility of children has entered the picture. (And no, I don't think people should have children outside of wedlock, but that's another discussion.)
Maybe what's needed is a credit-report for dating. Is this someone who missed an occasional car or credit card payment? Have they lapsed in the past seven years? I'm pretty sure Google could come up with a way to scan social media data to produce a report for relationship fidelity.
Now there's a dystopian sci-fi-premise!
ha! i like the idea of a credit report for dating (though, only for fiction purposes....i can't imagine a real world where that would be rule rather than the exception).
it's possible my ideas are tainted because of HOW MANY of my exes have cheated on me; i just can't tolerate it any more, no matter the reasoning behind it. but that's just me.