Argh. I hear you. I'm sad to see you going through this too. I have an S/O who is suffering with depression right now and is LL when he used to be HL much like I have been for my entire life. Things started out like bunnies and slowly dwindled and he's been saying he will "sort it" and work things out for a year. He ALSO makes jokes now when we're going to get down or i'm trying to get down - that also bothers me! I explain that I'm cool with having fun but I don't want sex to be a joke all the time, I need passion. We have literally just had a fight about it 20 minutes ago which I feel awful about but currently we are apart for a few nights (we live together) and I just want SOME sign that he wants me sexually even though he's all "I want you more than ever". Very similar to your S/O.
Mine is very affectionate and lets me and shows me how much he loves me all day everyday apart from sexually. It's a killer. But one thing I tried that helped me was that I imagined it the other way around. I am no stranger to depression so I imagined him being upset with me or angry because I wasn't having sex with him and feeling that pressure to do it, and that would be totally uncool!
All of a sudden, I realised he is NOT responsible for my sexual happiness. Much like emotional happiness. I decided to start masturbating more, and doing things that made me feel good and things that turned me on and satisfied me instead of relying on him and all of a sudden, that somewhat resentful feelings of rejection went away, because I realised it was his body and he didn't owe me anything. If it's something I want for my body, then I provide it, just like we don't owe anyone else anything from our bodies that we aren't 100% comfortable with. This helped me and empowered me and somewhat released me from the chains of that "acceptance and love" that purely comes with sex and probably insecurity.
Similar to you, I do lose my cool sometimes and I do start to feel down but my s/o never says anything bad towards me, he just apologises and wants to do better which makes me feel terrible and also perpetuates the cycle.
He said to me in the tiff today that he's becoming increasingly aware how dissapointing our sex life is becoming or ever growing as things don't get sorted out as fast as i'd like them too, which makes him feel worse... hence the cycle.
It's breaking that cycle we need to find, but i've found taking control of my own needs and satisfaction helps both parties and also helps you deal with "rejection" better as you see it as something you don't need to feel loved because you can do it to yourself.
I hope that makes sense! I haven't slept and still up reeling over mine and S/O's fight because I feel awful.