I'm sorry to hear about your situation. I know first hand what it is like to have someone you love dearly become disconnected. My husband, but boyfriend at the time, suffers from horrible pain daily, but then he started having trouble with his family. He chose to withdraw, going days without speaking to me, even picking fights.
It was very difficult to go through. I wanted to help, but honestly, he just needed the time. I refused to go away and eventually I understood that his withdrawal was his way of self protection. He feared I would leave him, so if he ran me off first, he would be in control. Only by sticking it out did I prove to him I wasn't going to leave. That I wouldn't be overwhelmed by his health and that I truly loved him.
There were many tears on my part, but I stayed with it and couldn't be the happier for it now. We married three months ago today and I am the happiest I have ever been! So, chin up, there will be better days ahead! and I am praying for you.