You are being taken advantage of. Providing an audience to this kind of person can suck the life right out of you. Of course she needs a friend and deserves some attention and some compassion from someone who is her friend. However, in a way you are harming her. This is a recent insight I've developed after years of me being a magnet for people like that. When you reward a person (with attention) for dysfunctional behavior, you are helping them stay in a dysfunctional mindset.

No doubt your friend honestly doesn't see where she's getting hard to take. It would do her good to not have her trying behavior reinforced. You could gently say, "Let's put aside negative thinking for awhile and focus more on the positive." If the gentle redirection doesn't work, then you may have to firmly disengage with her when her conversation keeps going in a dismal direction. You don't have to announce that you are doing so. Just do it. Excuse yourself and say you have something else to do. (Make it up, if you have to.) She'll eventually catch on that she needs to engage with you more positively, if she wants your company. This helps her too. It helps her to stop perseverating over subject matter that is keeping her in a negative mental state.

Sometimes it does a person good to be listened to about something that is troubling them. But when a person gets to sounding like a broken record where the needle is stuck and they're kind of "on a loop," they are not using their mind in a fruitful way. Sometimes the person may genuinely need redirection to get off this merry-go-round, or dreary-go-round.

Your friend has become self-absorbed and, even, selfish. Don't enable that - for both your sakes. Since you value the friendship, you are just the right person to help her rechannel her thought processes.

Otherwise this one-way friendship will peter out. You'll get sick to death of her, and you'll find yourself avoiding being stuck listening to her. She, possibly, won't understand why the friendship dwindles. Help her to understand how she needs to change so as to preserve the bond. Don't patronize her. Use some humor. Include some expression of affection: "Jane, my dear friend, we are going to talk about something more positive. You are kind of stuck in a mental rut, and I'm not okay with just leaving you in that rut." I truly believe that people can be told very difficult things, if they hear love in what they are being told . . . if they hear a hopeful message that they can be better than how they've been acting.

A friend of mine said something really nice to me that made me love her. She was referring to a recent occasion where I got out of line. She told me it "was so out of character" for me to have gone off the way I did. I thought that was a very sweet compliment. I'ld gotten upset and flipped out. She conveyed that she thought I was better than that. I thought that was generous of her.