And what shall the gentleman do? "Well I love you but it's probably a mistake because I'm probably a mess myself so let's just walk away from it?" Even were this situation as bad as you imagine that strikes me as a soul-killing response to problems.
I agree this looks rough but I've seen some very bad situations that ended up looking like something from Disney. Those situations had heroes and those heroes went through some crazy shit. There is hope.
So. The guy is going for it. Are we satisfied to comment that it will all end in tears? Or shall we look for some way to help it to a better end?
It isn't enough here to note the risk. You have to offer something constructive. I don't say "not hard", perhaps this relationship is a terrible idea and if it is so then it is no kindness to pretend otherwise.
But the OP simply isn't going to hear "dude, co-dependent, not good". If you see trouble clearly enough to say so then you have a duty to offer some path around it or through it.
It is OK to size up a potential relationship and make a practical decision about pursuing it before you actually fall in love with someone.
For most people, starting a relationship with a severe schizophrenic is a bad idea. You're letting yourself in for a lot of suffering and very likely you'll further injure your loved one when you eventually leave because you can't take it any more.
I think part of growing up is recognizing that not every person you feel attracted to is actually a good person for you to be involved with. Letting feelings of attraction trump one's better judgement causes a awful lot of misery in the world (usually in much less dramatic but much more common scenarios).
I'm speaking of the general case here. As you say, sometimes seemingly reckless relationships do work out. Kas clearly doesn't regret falling in love with Sally and I hope that they go on to have long and reasonably happy lives together.
Absolutely.
But that size up should consist of more than simple pattern recognition.
I think part of what people are picking up on is that for all his generosity of spirit and love for Sally, he's decidedly unsympathetic to anyone else which suggests to me he's underestimating things. Was Mr. WoW a horrible human to begin with? Did he know what he was doing? Did he have the support structure you excellently advised about creating in your other post? Did he just love WoW or did WoW become his only escape from a situation he could no longer handle? Those aren't questions for anyone, just ones I might ask myself.
The simple fact is that you don't have the right to say that to someone, not ever. To consign someone to permanent failure, to even call into question their reality as a person ('broken') is unutterably cruel.
We all have the right to choose who is in our social life, and we have the right to choose our boundaries, as arbitrary and possibly awful - or healthy - as they may be. There really are people in the world that have serious mental illness, and it's okay to not want them in your life. But that does not give you the right to consign them to a label, and to predict their future, and to dehumanize them, calling them 'permanently broken'.
I'm still friends with her, but not particularly eager to try again with a relationship. We try to see each other once every month or two to catch up on each others' lives, but otherwise aren't in regular contact (because when we are in regular contact, bad things happen). Both of us are dating other people.
Also, back when I was a teenager I had many of the same mental issues she did. (Perhaps that's why I latched onto her, and why we have such a tendency toward codependency.) What helped me recover from them was not the people who did the darndest to help and bent over backwards for me, at the expense of their own well-being. That tended to actively make things worse. Rather, it was having adults in my life who served as solid role models, secure in themselves and their own lives, who would interact with me as a person but still set very firm boundaries. And they were relentlessly patient about this. It took about 5 years. You can't be relentlessly patient with someone for 5 years unless you are simultaneously taking care of yourself and carrying on with your own life.
I wish the author the best and hopefully something good comes from it, but my guess is that it will be a tragic relationship with tragic end results.