Hearing about what it will be like to be with someone with a challenge like bipolar and actually living it are not the same thing. Just because you told him what to expect doesn't mean he (or anyone for that matter) could really grasp it. I'm not making excuses for him, but you can say you warned him all you want, the reality though was apparently much more than he was able to handle. Better that he figured that out before marriage and children were involved.