(TL;DR: I don't need him to have an erection, but he gets so sad about not getting one, even when I tell him it's okay and we can have sex other ways, that we basically don't have any kind of sex anymore even if I initiate because he's too disappointed in himself.)

I am in a very loving relationship with my boyfriend. We align on so many things, interests, hobbies, and ways of thinking, but also in being very affectionate and cuddly and appreciative of each other. Our relationship is generally fantastic and nearly perfect, with quite a small amount of imperfections, except for one that is huge:

He has phimosis, which has given him erectile dysfunction. He didn't used to have it, and it was most likely caused (though we don't know 100% for sure) by scar tissue on his foreskin from a teeth incident with his ex not healing properly and making it too tight, and now his foreskin will not fully retract over his glans, making it painful for him to keep an erection. I feel he has now accidentally come to associate being horny with being in pain, because his sexual desires, which were once frequent and healthy, deflate constantly. He has now mostly stopped even getting erections.

He has been to the doctor and he prescribed him steroidal cream to try and loosen/thin the skin, but after the recommended weeks of use, my boyfriend and I agree that there is barely any noticeable change. I have been with one other partner who's had this issue before, but he was able to get a partial circumcision. In the country my boyfriend is living, there is no option for a partial circumcision, only full. I love my boyfriend's foreskin and would really prefer he not lose all of it. He feels the same. He also worries it would make him not recognize his own body fully anymore in a dysmorphia after having had foreskin for 34 years, and I have the same worry, and it breaks my heart.

We are polyamorous, and he says I can find someone else to satisfy my sexual desires, but I don't think he understands the implications of me being demisexual (aka it's hard for me to be sexually interested in someone until I'm emotionally interested). I want to have sex with him because its his personality and essence of who he is and how we laugh and cuddle and have fun together that turns me on, and having sex with another person will not satisfy my desire specifically to have sex with him.

When I started telling him about how big of a deal not having sex with him was to me, he put in a little bit of effort, but not much. It is now to the point where I am initiating essentially 100% of any sexual contact or flirting. I told him telling me things like how sexy I look and how I turn him on can help a bit, but I would love if he would actually touch me and keep going with that, and eat me out or fondle me or tell me he wants a blowjob or use the toys on me, instead of what he does right now, which is start to touch me, grab my breasts and kiss me, and then stop. He says the problem is that when he does touch me like that and gets turned on, he then quickly gets disappointed in himself because he know he won't be able to stay hard.

We have both been very sexual people in our lives, and now he doesn't know what to do with himself because he can't perform the way he used to, despite very much having the strength and stamina to do so, and I can't handle it much more either, despite how fantastic other parts of our relationship are. I think he has now started to accept that he's not going to have sex as much as before, but I can't accept that. I know it doesn't have to be that way, if the cycle of him getting turned on and then subsequently disappointed in himself stopped. I don't need penetration from his dick every time, I just wish he wouldn't get so discouraged and would do other things with me instead, but he's basically just...given up.

We've used pills, and unfortunately they don't have a very good success rate for him so far and they're also very expensive to even try. He is very embarrassed about this issue and it's hard on him when we talk about it, but I know that sex is a major thing for me and I'm not sure what I can do, it's literally to the point where it's almost easier not seeing him because he turns me on so much but I know nothing will happen. I've tried to tell him to go to therapy for this, but I don't know if he can get over how embarrassed he feels by it. But I do know that I'm tired of initiating, especially when I can tell it works and he gets horny, and then I watch as the libido just fades from his eyes. It hurts so much. I wish he would find it easier to initiate sex, fingering, oral, just any kind of sex, but he just ends up feeling helpless, and like he's "not enough". But I'm getting tired too and feeling like there's nothing I can do.

Is there any advice from anyone who's been on either side of an even somewhat similar equation?