By my standards of personal integrity in such situations:Both parties in the marriage.
how is the non-cheating party responsible for someone cheating?
that's absurd
if you're not happy, you can leave.
You either don't concur with that standard or you weren't aware it might be a extant standard. Either way, now you do know and how you manage/apply that knowledge is up to you. I'm not going to presume to suggest how you should manage/apply the knowledge.
- Cheating partner --> Obligation to reject offers from "outsiders"
- "Outsiders"
- Obligation to find out if the person who attracts them is already "claimed."
- Obligation, if one's "person of interest" is "claimed," to "back-off" in accordance with "do unto others as one'd have them do unto oneself."
I agree with your first bullet point. But I don't think any "outsider" has an obligation to the marital relationship. should they be cognizant of it? probably. but I don't see it as obligatory.
everyone can say no. there is no such thing as someone you can't turn down.