If you have a friend who is doing something a little bit careless or stupid, are you obligated to try your best to keep her from getting herself into trouble? Or do you just let her live and learn?

I have a friend who recently started fooling around with someone who's currently in a relationship. I know no good can come of it and I'm kind of disappointed at how selfish she's being. Why would she put herself in the position of the other girl? She says she doesn't want to be the other girl and knows that she wouldn't want a relationship with someone who cheats, but I think she's still continuing with the hope that something will develop. Why else would she ask him what was going on if she knew it wasn't anything more than a one night stand? And the guy is a sleaze. It's like her only standard is that the guy must be good looking. She can do so much better, but she never does.

On top of this, the two of us have another friend who recently started dating a new guy. We don't really like the guy or his friends. They're sketchy, we don't trust them. While I try not to be judgmental or intrusive, my friend has let this other friend know exactly how she feels about the relationship and they have gotten into a number of arguments over it. Meanwhile, she's making her own poor choices.

I guess I'm asking, what would you do? Do you make it your responsibility to try and protect your friend from bad judgment? Even if you're jeopardizing the friendship? Or is that doing more harm than good? Maybe people need to be allowed to make mistakes? Maybe I'm the one who isn't able to view the situation objectively and my friends' actions are actually more reasonable than I think? Is this none of my business?