These issues can be intense, and you never know what will happen. And you'd like to prevent that.
I was once moderator in a forum, where we had no rules about this. Here, there's the rule that if some psychological ....er complications boil up, that you don't engage, delete the discussion (I think), and if necessary send over the advice to consult your doctor/therapist/priest (not sure if we had a link to a general page where to find help).
So I was mod in a forum there. I was on late at night, one of the guys contacted me via ... ICQ at that time, I think. We talked for a while about various things, which spilled over from a forum thread, where he was getting paranoid if or if not his girlfriend had cheated on him. I had no XP, we were talking for a solid 2h over ICQ about various things, mostly his issues, but also more about his GF, and also about this alcohol problems, and that he had been dry for a half year. The whole conversation worked him up a lot, he couldn't let it go about his GF, despite that I was sure there was nothing.
The conversation ended with him saying that he'll go to the next gas station, to get a six pack of beer.
I felt so crap. It felt really terrible.
And you know, the biggest psychological issues, the most pressing ones are probably suicide.
You don't want to have a discussion where the last post from a person is "I'm going to kill myself".
Not only for the person, but for everyone else who's in that discussion, and how they'll feel.
That's why we don't have these discussions here. Nobody is prepared for that. Go talk to someone, who's prepared for it. The people are getting paid for this. Go talk to them.