I'm a little late to this thread, but starting from the top:
Would you stay in a marriage if your spouse Cheated?
If the other spouse cheats then I'm not exactly sure whether there's any longer a marriage to stay in. Seems to me that the decision has already been taken out of your hands.
I think the cheating begins in the heart, not in the physical act. If I'm in a situation where I feel that a woman is having more than just a friendly good time with me then I'll bring it up with my wife: "Hey, did that seem a little strange to you back there?" Her answer may be "You wish, you geezer" but the point is that we feel comfortable enough in our relationship to discuss the question. Same with a guy who's overly friendly with my spouse, although her antennae are much more attuned to this issue than mine.
A cheating spouse apparently didn't feel comfortable or secure enough to have the spousal discussion, let alone maintain their fidelity contract.
Humm, it appears to me that Warren Buffett and his first wife made an arragement that worked for the three of them.
Yeah, well, gotta read Alice Schroeder's interpretation of the situation.
Warren routinely neglected Susie mentally, emotionally, & physically, and didn't at all appreciate how she felt about his very public "work relationship" with Katherine Graham. (By "neglected" I mean that Buffett's lack of emotional intelligence & social intelligence borders on Asperger's.) Susie eventually decided to live more of her own life (since Buffett had apparently abdicated by apathy) and moved out. This included an affair of her own. But Susie felt enough concern for Warren that she asked Astrid to keep an eye on him. Only Susie & Astrid know the arrangement they made, and Astrid ain't talkin'.
While Susie felt free to carry on an affair with another man, she probably didn't feel free to complain about Warren's "relationship" with Astrid. Schroeder even implies that Susie carried on her relationship long after she reassured Buffett that it was over.
Frankly, from Schroeder's description of Buffett's behavior by the time Susie moved out, it's hard to imagine him having a physical relationship with another human.