Who is in the wrong?

Ok, so I don't fully know the story nor do I wish to know it. But a family member of mine married the really nice guy who brought up her girls really nice guy and is just as close family as she is.

Now she got a new interest she got into motorbike/scooter riding over 2 years ago and she had met another guy and cheated on her husband.

Ok, so who is in the wrong?

The Nice Guy for not leaving?
The Girl for cheating?
The Guy who new she was married and new the nice guy for cheating?

Now I know a lot of people are going to say "Derp blame her its all her fault" but I can't really do that as she is close family.

 

I can barely understand the story. Reword it better. From what I can slightly understand, it seems the girl should be blamed. Being a close family or not, it doesn't change the fact of who did wrong. Who did the wrong is to be blamed and it doesn't matter if she is the closest thing in the world.

 

That ^

They're all in the wrong really..
The guy should leave her.
She shouldn't have done it.
And they guy who knew she was married shouldn't have done it.

However she is mostly to blame, I'd say 90% of the blame is on her.
Although saying that, I don't think someone should be forced to be with someone simply because they're "married", if you don't love them any more you shouldn't have to stay with them.

 

Looking at what you've written, i'd say the girl is in the wrong for going out and cheating on her husband. If there was something lacking or wrong with the relationship she should have brought it to his attention so they could work it out, eliminate the bad and move forward with a stronger relationship.

 

From what you have written, I'd say the wife and the man she cheated with is in the wrong. She should have known not to cheat on her husband. The man she had the affair with is also in the wrong, for not leaving the woman. He most likely knows she's married, and he still slept with her by the sounds of it.

I'd place about 90% of the blame on the wife, and the rest on the guy she had the affair with.

 

tbh, its not to the fault of the nice guy who didn't leave.

It appears that the "nice guy" has TREMENDOUS feelings for the girl.
The girl is confused.
The other man is being just that a man. He has mutual feelings with a girl so they hook up, I'm in no way sayings its right, but it is what it is.

So its really about 95% blame on the girl and 5% blame on the guy who she cheated with. The 5% only comes from him knowing she is married and continuing on.

However, without the whole story it really is impossible to say.