When a woman or man cheats, is the current wife/husband, boyfriend/girlfriend ever held at fault for weakness?

I've said the same thing, but slightly differently. I think there are reasons that some people cheat. Sometimes, like in your friend's case, better reasons than others. I think there are people who cheat because if they divorce, their spouse will make it very difficult for them to see the kids. They don't know how to get out of the marriage in a civil way. I think in your friend's case that he still has to divorce this woman because he will be happier in a new marriage. My kids are fine after my divorce, but it really depends on how the divorce goes. My ex and I work things out together and that helps. Staying, no matter what his reasons, don't make sense because eventually his girlfriend will leave the relationship, if he doesn't end the marriage. She will only be so patient.

A cheater is 100% responsible for their behavior, no matter how crappy the relationship that they are cheating on...that doesn't mean their partner is a gem and has done nothing wrong, but it doesn't excuse the fact the cheater decided to step out and betray the relationship rather than fix it or end it...

A cheater is always free to leave an unhappy relationship, and since cheating often does lead to divorce/break-ups, it's pretty stupid to cheat and trigger the relationship ending instead of just ending the relationship and not being a cheater...

The cheater's relationship partner may well be negligent in their role as a partner...but that's not an excuse for the other person to cheat...

The cheater is held accountable because there are other options besides cheating. You can work with the other person in the marriage to fix the issues or end the marriage. Cheating will NEVER fix marriage problems - it just adds tons and tons more as well as very much collateral damage when things come out (and they usually do).

Cheating is a huge betrayal, causes much destruction (to more than just the couple - especially if children are involved), is very cowardly, and is very selfish.

The man you referred to chose his wife (you saw the issues that he chose to ignore), had children with her, and because things aren't going as he wants he is cheating on her and his children. He had many, many other choices before and after marriage and kids and in the end chose to cheat. He is responsible and at fault 100% for breaking his vows and cheating - period. And, he bears as much responsibility as her for the state of the marriage.

It takes two to make a relationship work or crash and burn. Both partners have equal blame in the relationship's problems.... but it's an individuals choice to cheat. The problems may have helped contribute to the choice, but it's still an individual choice. This is why we come down so hard on cheaters, because while their original relationship had problems, it didn't give them the green light to cheat. Either you try to make the situation work, or you leave.

While what you say is true the reality is that if we practice what you preach there probably would not be a couple left where each of the spouses would not cheat on each other. This would simply make the whole world one big orgy. When we got married we took vows and should make every effort to uphold those vows. (ps. I am a male).

Maybe her attitude is a direct result of his actions. Ever think of that?

Sure, the other spouse needs to step up and make their partner happy in whatever way they can, but the cheater also needs to learn how to keep their pants zipped.

He liked her for some reason at some point and vowed to be faithful. No, she (regardless of how hateful) is not at fault. Rather than acting like a coward he needs to help build a happy home. Perhaps her hatefulness is a result of his behavior too.

This is blaming the victim,. The cheater did something wrong, not the person cheated on.

It doesn't matter what is going on at home, there is never a valid reason for cheating, period.