Hey, I used to be an aerialist! Side-gig, not a full career, but many of my friends are on the Euro and new-American Euro-style dinner circus-theater circuit
I used to wonder why I always had more pain, fatigue and chronic “injuries” than women twice my age in my troupe and community. I chalked it up to being a full-time neuroscience major, spanish minor and gigging aerialist teaching classes to boot!
But again, others around me were keeping up a schedule that packed plus motherhood in some cases… And my motivation/energy often passed up my musculoskeletal tolerance till about 2009, when debilitating fatigue rolled in more frequently. (Currently, its been ruling at least half of my days in the past 6 months, but I’m beating it back little by little bow that I know how to work with my reality rather than fighting and running from it, plus plaquenil building in my system the last two months, and accepting to take anti-inflammatories rather than “tough it out.”) It’s all finally making sense to me now, and to me it’s more relief to know, though sometimes scary to think what can come with it… But I am one to see it as, “this is my reality, and it would still be happening without knowing what it is, and knowing about it gives me power to do something about it!”
I’m only 25 and currently single, so I can’t claim to be the love expert… Yet I have failed and observed enough to know a lot, including watching and admiring friends in extremely happy relationships! Which I have never had, and often blamed on my own complexity and demandingness. Newly diagnosed as well, but been one with “issues” a long time. It had DEFINITELY affected all of my relationships back to the simplest ones in high school. One thing I was extremely glad to have recognized already was how some men (and boys, back in the day!) I’m with have a natural and easy way of calming me down and making me feel understood and supported, just by their manner, while others really send me through the roof making every problem worse in spite of good intentions! Those ones who “fit” me in terms of harmony didn’t in other ways, or had other priorities and moved on. Just as well, I’m honestly still in “learning” phase about relationships and just starting to have an eye to “settling down” in the next few years if I’m fortunate enough to find something’s that works for me 
Still, a CRUCIAL thing I’ve found is that I have much more peace, success and satisfaction taking care of myself, both my health and my emotions, than being with someone destructive. And I’ve really felt what you describe of the “sometimes” destructive relationship, of which I’ve had several including one that lasted almost four years and got worse over time! I think if someone treats you badly any amount of the time, knowingly, without it being a mistake that is apologized for and FIXED immediately, is far worse than not-worth-your-time, but actually displaying warning signs of future more serious pain or even abuse. At best, and giving him the biggest benefit of the doubt (which I tend to always do as the loving-forgiving type… Callousness in my words is just reflecting the balance in view I’ve had to build for myself…), you could see it this way: he just can’t cope with your truly higher levels of needs and intensity (which probably also contribute to your beauty and power as a person… Find someone who loves you more for it rather than resenting it!) You can see my bias towards you deserving the love and support you need, even if it’s just through friends and family and yourself during this hard time, but I also am oriented toward being pragmatic about relationships “working” and “not-working”. If he he is drowning in your depth, is that good for him either? No… Maybe he has a relationship disability and needs someone easier to digest, and you have a medical condition and need someone who can hack it. A quote from Marilyn Monroe, of all people, says “If you can’t handle me at my worst, you don’t deserve me at my best…” That was posted by a friend struggling to get out of an extremely manipulative and miserable relationship in the midst of her MS diagnosis last fall at barely over 24 (sad it took such a huge blow to her own health to get her in gear to take back her dignity and emotional health, but amazing how she harnessed strength to take it all on!) Your reality IS your reality, and you are entitled to living it and being loved for it!!! It’s also true that you are responsible to manage it, and in general directing the course of your life… But I see you having no trouble with this just by how you describe yourself… Though Marilyn’s statement could be used as an excuse for selfish or poor behavior and entitlement, your concerns for easing your burdens on others clearly show YOU have what it takes to negotiate a mutually supportive relationship; his cake-tantrums that blatantly ignore how his unfounded rage hurts you shows he does NOT! I don’t know his age, but if he’s older than 22, then his actions are no longer even developmentally appropriate! One thing that hit me hard thinking back on excusing guys for needing to “grow up,” and finding hit-or-miss success dating older, was realizing how thoughful and patient the boyfriend I had for the first half of high school was (at age 15! ), despite my own struggles and major family drama at the time, leading to seeking a ton of support from him and his family… He’s engaged now and gonna make that girl so happy
Comparing that to guys ten and 15 years older than he was then who couldn’t internalize even one way they hurt me or let me down… No idea what I was thinking staying with them beyond those first few battles! One time it was years of pain, now I limit it to months, or in the past year and a half, just weeks! Some people are sensitive and caring, others aren’t. This is not a gender/age thing, though thise can influence experiences and communication styles to some extent… Because we are all unique and unpredictable, someone caring will occasionally get it wrong, then recognize it or hear you when you bring it up, and apologize and try to learn without blaming you! And maybe ask for your cooperation or compromise, but be respectful and clear in doing so! I’d say with a year or so invested with him he’s not learning fast enough how to be with you, and aren’t more years together just going to deepen those grooves of resentment, pain and dependence?
My stepmom warned me a few years ago that relationships get harder, not easier, over time, even as they deepen and get better! Make sure yours is golden before you get too far in… One of my friends, a major role model 5 years older than me, is in beautiful, strong, inspiring relationship, the kind whose wedding made a whole crowd of people absolutely high on the sheer joy… She is actually trapeze partners with her husband and thus is with him 24/7, often away from all other friends for contracts, under intense pressures and in a constant mode of critical improvement and self-management of their act (i.e. some of the toughest relationship circumstances imaginable…) Her comment on finding each other 8 years ago? “Everything just felt so easy and right, and I didn’t feel like I was such a problem anymore!” They are luckier and much closer than most, but I have had my own fair share of experiences that point to some people naturally fitting while others make everything an uphill battle for each other. And some people are just jerks, even though we want to believe in them. So, I would say tell him the ways his closed-minded hyperreactions are hurting you more than helping, and that he needs to think about how those behaviors would impact anyone, not just someone with high challenges and needs! Or, if thats more risk to your well-being, walk away more cautiously and let him figure it out while he’s alone. He obviously isn’t too afraid of that to be treating you that way… Or is used to getting away with it and has a hard lesson coming! But I don’t take any of this lightly, and I do know these things are harder and far more complex from the inside, that there is always the concern about baby-with-bathwater and a fear of the unknown… But in all honesty, even if you do have beautiful things between you, it seems to be souring by the ways you overwhelm him and he undermines you. I say get good friends around you, keep in mind what you could find instead, know you can take on your challenges independently, and let this one go! Even just doing so may remind you of your strength to take on your lupus, and your confidence and competence will be wildly attractive to many suitors… Most of all the ones who want to see you thrive rather than cower 
That last part I can say has been working for me… In the last year and a half of raising my standards or really throwing out the search in favor of self-development, I have had more offers and advances than ever, from a more “eligible” crowd of bachelors (plus of course the steady stream of desperate ones…) I’ve stayed open minded to try it out, but if it’s getting difficult early on I instantly prioritize my need to keep on track and move on. Right now I have a good balance for the past 2.5 months with a guy I started seeing, slowly and cautiously, just a few weeks before my diagnosis (and definitely in the heat of struggling with symptoms!) We have kept things moving slow; I’m busy with my lupus and redirecting of my whole life plans, he’s on a big push with his acting career in addition to his existing music career (he has lead roles in two San a Francisco plays simultaneously this fall, continues driving to LA many weekends for film&TV auditions, and is releasing a self-produced EP in the next month! While holding down his steady half-time job!) Despite how swamped he is, and honest in stating his priority on his goals rather than getting caught up in a relationship, he is remarkably attentive and understanding when we talk, and the time we spend together about once a week (about to decrease due to his rehearsals starting up) is extremely positive, worthwhile, comforting, and teaching me to trust more again. It’s great for me right now, low pressure and high reward, and partly so because we are communicating what we can each handle (and fortunately are matching in our level of commitment… Minimal, but eager.) I might have to say goodbye at any moment if he relocates for a movie, and maybe our lives will never really line up well for what we each need into the future, but a more limited interaction with someone who makes me feel so good is just what I need right now. No sense in suffocating him trying to demand more, especially when it’s so important for me to manage my own growth in my emerging reality. Also no sense in staying any longer than I can stay comfortable with a low-density interaction, but I’ll run with a good thing for now and change course as needed. I told him my guess was about a year till I’m going to be ready for something more serious… And if he’s there with me he’s top pick. His skills in communicating and talents in working with me are worth a bit of patience to see if something bigger can grow later… And at least I’m getting a taste and knowing what kind of care and manner I like in case I need to look for it elsewhere to settle down. It’s great to have a reminder that people are good and kind, and even better when they understand you, and you can give and receive freely what you each have to give. If it stops being that, I’ll be glad to take the lesson for the road!
Best of luck and much love to you also. I know it’s such a hard road, both the lupus and the troubled relationship…especially when they intersect… Hang in there! Use this period to really feel and develop what’s right for you… It’s the major gift we receive along with what’s taken from us!