GalaGirl: Thanks for your message.
I read both articles, and have found many things with which I can identify. I am certainly feeling displacement, as well as intrusion and some jealousy.
I find it especially hard if she is sick or having a bipolar episode where she needs comforting. He is a natural counselor, and I am not. He's the one you go to if you need advice or comfort, and he seems to enjoy being that person, but that also puts huge demands on his time. Everybody relies on him, and can't do without him after a while. He's also best friends with his most recent ex-gf, which bothers me to some extent, but that's a whole other ball of wax.
I definitely think things were very rushed with the secondary moving in, and there is still some unresolved jealousy there because, while I waited patiently for over a year for him and me to become an official couple (with us having known each other for over three years before that), she was officially his girlfriend after only about six months of us meeting her.
In terms of what I need from them, I'm not really sure. He gives me all the reassurance in the world and tries his best to put me first and show me that I'm still his priority, but with her living there, it just doesn't feel like that to me anymore. I don't even want to visit him at his place because she's always there (they're both on disability and uninterested in finding even part-time work), and I don't feel like seeing her until I have to at events.
I've started wishing that I could go back in time and undo my suggestion of us becoming poly, but I had no idea at that time how it would turn out. Back then, she was medicated and a lot more stable than she is these days, but she had to stop her medication to save her kidneys. Since then, she's been bouncing around between different meds, and nothing is working particularly well. She's all over the emotional map, and it's very hard to deal with.
All in all, I feel like I'm almost done with the whole relationship, the one with him included. I eventually want to get married; he has this idea that he won't even propose to someone until he's lived with them for at least five years. Given that we're never going to live together as long as she's in the picture, I don't see him ever proposing to me.
I keep thinking that maybe I just need a break from the relationship, but then I realize how depressed I get when I don't talk to him. Unfortunately, what I seem to need is something that can't happen: I need her out of the picture. I'm afraid she'd just die without him.