I came across this in NOW! Magazine. Kinda sums up all you need to know about the relationship-rescuer types.

"... sometimes we fall in love with people who, for whatever reason, simply aren't healthy enough to love us back. When you realize you're falling in love with a hopeless mess, you don't hang in thinking your love will cure them. It won't. Love is great, love is grand, but love ain't chemotheraphy - it's not going to magically turn some sick f^%$#@ into a healthy f^%$#@."