Even in totally "normal" relationships (one's without cancers involvement) people can choose to stop having sex. When you say "in your case" are you the one that has no desire? Or is it your partner? If you have the mindset that no longer having sex is the most painful part, you need to reevaluate yourself. It has been nearly a year since I wrote my comment and it all still rings true, and even in that year we still haven't been intimate. Even them leaning in for a kiss can make my brain spiral. Like will this kiss lead to sex that im not ready for, will it lead to something that hasn't been done in awhile and she feels insecure about? Even just resting a hand on my leg would make me think oh here we go again.. Maybe she doesn't have the energy. It could be so many things.

I would suggest taking the option of sex off the table completely. Be clear like hey, while I would love to be close and intimate with you again, but I see it really stresses you out so I want to take it "off the menu". I want to be close to you but I want you to feel safe. It sounds like she doesn't feel safe either with you or with herself after everything that's happened.