Hi all, this is my first post here. Sorry it's super long, I'm working through a lot of feelings and could use some insight/support/advice.
This is all in regards to my on-again off-again boyfriend of 1.5 years. We are both in our mid-20s. He has never been diagnosed with BPD (and I hope this doesn't make me unwelcome here), but I am very familiar with the disorder and find a lot of his emotions and behaviors to be similar to someone suffering from it. He has been diagnosed with PTSD & bipolar at different times, from very short-lived attempts at therapy in the past. Ironically, I am the one who has been diagnosed with BPD- again, I hope I'm not making myself unwelcome here. After years of searching for the proper therapist & medication, I no longer fit the diagnostic criteria (so yes, there is hope! I can confirm that recovery is possible!) I'm not going to pretend that I'm 100% cured. I still struggle with some negative thoughts, and I don't always behave the way I'd like when I'm in distress, but I think that can be said for everyone!

I'd like to preface by saying I have no intentions of leaving my partner. I know what I am describing does not sound ideal or heathy, but is that truly possible with two mentally ill individuals? I may be focusing on the negative aspects, only because I need support. Things are not always terrible. When he is "stable," we discuss openly and honestly discuss our future together which seems very tangible at the time. He has told me on countless occasions- and he is not the most open or emotional person- that he could never see himself spending his life with anyone but me. Mainly because I put up with his ___, I believe. But we complement each other so effortlessly. We are disgustingly codependent; I need to need, while he needs to be needed. But we are self-aware and accept these aspects of ourselves.
Obviously this euphoria eventually comes crashing down. I'm all too familiar with this. When he breaks up with me via text, offering no explanation and blocking my number, only to drive me into a panic calling him 25 times in a row, he'll eventually tell me I did the "right thing." I get it. I played that game all too well. I always wanted someone to need me that badly. Stalk me like prey, beg. When he tells me he cheated on me, just to "test me and see if that would make me leave," I get it. All the mind games, the power struggles, constantly making sure they really won't leave you. It would be the downfall of all of my relationships; turns out I hate being in a position of power. But I get it.
Our temperaments are completely yin & yang even without our disorders; while I am cheerful and emotionally explosive, he is one of the coldest and unfeeling beings I have ever encountered. Yet when he is "stable," he sometimes works past his reluctance to open up and tells me where his behaviors are coming from. He has a huge fear of abandonment. He's told me that any hint of rejection or perceived abandonment and he will leave me in a second. He needs to feel "needed," and in control of the relationship. Any time that he feels that I'm getting some sort of power in the relationship he'll pull some kind of messed up stunt to bring me down, because in his mind, as soon as I have any kind of control I'll hurt him. And this, I understand.
What I don't understand is what seems to me like a fear of engulfment. I understand the "pull," as I have done my fair share of that, but not the "push." There will be days, weeks, sometimes even months where he doesn't speak to me. This is quite unlike the times when he goes away while saying something hurtful; then it is pretty clear to me that he is crying out for attention. In those situations, he returns within a few days. This seems to last longer, and begin out of the blue. At first I considered that perhaps it was a depression sort of thing. I know that when mine flares up, I avoid repeated calls from even my family and close friends. But it has been 2 weeks, and I have called him multiple times a day. I know that the rational thing to do in this situation is to give him space. But this is really playing on my lingering abandonment fears. He's always come back, but I can't help wondering "What if this time he doesn't?" We've never really discussed it much, to be honest, outside of both admitting and accepting that we have deep-rooted emotional masochistic/sadistic needs. By the time he is speaking to me again, I'm so relieved that I don't want to stir things up.
I'm certainly not trying to virtually diagnosis him, or anything of the sort. There's clearly some deep issues going on there that even he can't quite get to. I do feel that many of his behavioral patterns and thought processes are similar to mine were before recovery, although I could be projecting. I've just never personally dealt with this sort of extreme silent treatment or emotional pushing away. Hoping (for my sake, certainly not any of yours) that someone has been a similar situation ... I'm regressing quite a bit, and could use some advice. Sorry again for writing a novel!