I have found myself in the same situation..even with making friends. It may not even be apparent at first, and then a couple of months later I find out the new friend has some major issue, most common with my gf's has been childhood sexual abuse. I have been told I am very maternal so I guess I attract gf's who have that need for a mom figure. I have also been with '3' men who had schizoaffective disorder...and the first one wasn't diagnosed until after we broke up. my current bf has mood and anxiety issues. I often wondered 'what did my ex husband have?' he was the most normal of anyone I have known but was unable to deal with me.
I don't really have advice, just want you to know, you aren't alone.
(((HUGS)))