I think you are totally doing the right thing by being patient, loving, and understanding.It sounds like that's exactly what your partner needs right now. While I've never had anything so traumatic as a mastectomy, etc, I did have a similar experience several years ago.
I had trouble giving birth to my son and ended up having an emergency C-section. My OB/GYN would not let me leave without a prescription for some kind of birth control.Because I was breastfeeding, my options were extremely limited. I ended up choosing Depo-Provera, a hormone shot that was administered every three months or so. It has a ridiculously high success rate as a contraceptive, and I soon discovered this was because:
1. My libido totally died
2. I was as dry as the Sahara, and any attempt at sex was like trying to slam a railroad spike through a peephole
3. I was often in a homicidal rage, and my husband was afraid to come near me
I was on Depo for nine months, and it took another six for the effects to totally leave my system. During this time, my husband became bitter and downright nasty because he wasn't getting sex. His attitude of entitlement made me even more asexual and angry. I gave into him a couple of times because I was hoping to improve things between us. Even using nearly a tube of lube, sex was still very painful, and I was sore for days afterward. This made me resentful towards him, and started the vicious cycle again.
We're divorced now, not because of this incident, but because of the same underlying problem. He was selfish and impatient, among other things.
I think there are a lot of sweet men on this site who treat their women right. Kudos to all of you.