We all have people in our lives that truly offer nothing positive and we really need to end the relationship. A friend shared with me what was said to a person like that; I thought it was done lovingly, tactfully, but honestly. 

"I have felt for some time that there are parts of you and your story that have been off limits to me. And that's fine. I don't need to know it all. I have told myself that maybe you are totally open with a parent or a therapist, or with one of your women's groups. (Or maybe my conception of vulnerability in friendship is off base? That could very well be a big piece of all this.) It felt like the right and gracious thing to not pry into what it is you struggle with or what keeps you up at night. But when it comes to someone that I am going to invest time in and stay in touch with, I feel like I need more for it to be a mutual endeavor. I know some people try and juggle dozens of friendships, but I have decided that is not my speed. -So for me, I made a value judgment to phase you out of my life for those reasons."