Wow. I think this may be the first time I have ever agreed with you
I have never, ever for even a moment had any reason whatsoever to suspect that my husband has or will cheat on me. But if he did I think (and hope) that he would tell me. We have that kind of respect for each other and that kind of honesty in our relationship. And, I do not think a "one night stand" could extinguish the intense love I have for him--nor his for me. So, I would think we would work through it. I am sure it would be devistating and difficult---but giving up on us because of one mistake, ANY mistake, seems much more devistating to me.
I am surprised by the number of posters who "threatened" their spouses before getting married with what they would do if there was ever cheating and those who continually say things to their spouses or friends about they will leave immediately, etc. DH and I talk about everything. We always have. We know each other backwards and forwards and inside out. YET, we never talked about this. I don't know it seems like if I were to say "if you ever cheat . . ." I would be indicating I think that is likely and he NEEDS a threat to keep it in check. Since I don't think it is likely at all, why threaten? I also do not say "if you ever murder someone I am leaving instantly" or "If you ever take our life savings to Vegas and blow it all in one night I will destroy all of your prized pocessions and then leave you." It just doesn't make sense to me. I guess part of it to me is that when DH and I got married we saw it as our whole lives are now intertwined--not just our sex lives; so their are plenty of things which COULD betray our trust in each other--not just this one--and by getting married we were committing to be there for each other in so many ways that signaling out this one seems silly.
As far as someone else knowing and telling me. Yeah, I guess I would want to know (for the health reasons at teh very least). I would hoe my friends would give DH a week or so to tell me himself first and I would hope you would really know hat you were talking about if you did. If DH cheated and did not tell me himself that would hurt me much more than if he did tell me (I think--don't really know thank goodness).
As to the new question. I honestly cannot quite imagine DH having said to me "I hope I never cheat on you." Both of us believe we absolutely won't cheat--why else would we be married. But I know sometimes things happen you do not believe will and sometimes we humans do things we do not think we ever will.