I'm not really quite sure what to say. Because you are the only one who can decide whether you choose to be around to support this friend as she (I'm just going to call her a she) goes through a difficult time, or not.
My experience with this sort of thing is that people take their own time to process things, especially things that are really important to them and their future. Your friend may feel that there is something worth holding onto, even in the face of so many problems, and she just isn't ready to let go of it. The fact that you are impatient with the process shows that you may believe that she should adhere to some sort of schedule (yours), or that there is a limit to how long someone should try to work on a relationship.
In my own situation, I've spent both a lot of time, and very little time, processing the end of relationships and/or trying to make them work. My experience is that there is no set formula, nor is there a set timeline. Your friend must simply do what she thinks is best for her, and be true to herself, and you must simply realize that the only timeline that is going to work for her is hers.
I, too, have been frustrated in the past at a friend's seemingly endless back-and-forth with her partner. It was hard for me to listen, because I was so tired of hearing the same thing. And I admit, I did pull away from this person eventually. Not something I'm really proud of, because I never told her why, but there it is. But I also learned that there was nothing I could do to accelerate the process or make it go away, as hard as I tried to make her conform to my ideas about what she should do.
I find a lot of similarities in your friend's situation and my own. I try not to burden my friends with my problems, but I also struggle with not talking about it at all, since it's such an integral part of my life. So my attempts at sparing my friends the back and forth ultimately put stress on me, because not only am I suffering the problem, but I am also suffering keeping a lot of things inside that are really at the forefront of my mind.
For example, I'm aware that you don't want to hear any more about my problems with S. I have obliged by not talking about it. But recently, it seems, I violated this by telling you something about what was going on with S. and me. The reason I elaborated was so that you would be spared the discomfort of calling him up to go over to the workshop and finding out later (like, on the way to the workshop) that something had gone horribly wrong with our relationship and you didn't know about it.
I wasn't asking for advice, I was simply giving you what I thought was relevant information. I also think that I need to at least let my friends know when I'm completely stressed out and having difficulty, especially when I'm talking to them frequently. Otherwise, I just appear to be a ball of stress for no reason.
All this is to say, I don't know what you should do about your friend. Only you can decide that. If you can't give unconditional support, I would advise letting her know and simply pulling away. The downside is, it could mean the end of your friendship, depending on how your friend feels about it. If you decide to stick in, though, it's a conscious decision not to be frustrated and complain, because it is a choice you are making, and your frustration would end up driving you apart, anyway. Maybe your friend would agree to some kind of "Don't ask, don't tell" policy. But I can't imagine that in my own situation. It would mean sometimes faking that all is well, and stuffing my feelings about things that are really important to me. I don't want that lack of authenticity in my life.
