I am getting married to a wonderful man next month, but these past few months have not been very fun for both of us.
I suspect that I'm a lot like your bf. I am the one who doesn't want to talk about things and try to hide everything from everyone. My fiancÚ tries so hard to help me out, but it's just not natural for me to share everything. He really does do everything he can, but I'm just really hard to deal with sometimes!
We've worked it out so that I'll tell him every time I see him how I'm feeling. That way he knows what to expect. Like I'll say "My hips are really hurting today and I feel really nauseous so I'm just going to hang out on the couch tonight." Then he knows not to push me to hard to cuddle or be intimate because I'm too miserable.
He too felt like he was being rejected all of the time because I just felt so horrible. It was really hard on him. We went to my counselor together and she said the best thing for the two of us right now is to stay in communication.
I would really recommend going to see a counselor who specializes in people with chronic illness/pain. They at least know how hard it is for the partner with the disease.
I will tell you, that even though I'm with my fiancÚ all of the time, I still feel very alone sometimes. Just because even though he tries to understand how I'm feeling, he will never really be able to.