Healthy Testicle Or Not? Fertility?

Hello,

i am getting married soon to a man who will probably have fertility problems. About thirty years ago, he had a testicular infection that swelled one testicle and caused great pain. Within the few years after that, his testicle slowly shrank until one was completely gone. He can't remember what the name of the infection was, but his doctor at the time told him that he should have no problems fathering children. About 15 years ago, my fiance was thinking about the possibility of having children and had his sperm checked. At that time he was told that his count was "low to mid" but he doesn't remember any details. That doctor told him that he could probably still have children, but it may be difficult. Now my fiance is 50 years old, which in itself is going to cause problems! But, he has also spent the last 25 years relying on nothing but withdrawal for birth control without ever having an accidental pregnancy. He's never actually tried to conceive with anyone, but just the fact that it never accidentally happened makes me wonder if it is going to a problem now that he is ready to try.

So here's my final issue... He gets really annoyed when I try to ask him about it:
the testicle he does have is absolutely nothing like any I have seen or felt before. I cannot feel a firm ball at all, just a small amount of squishy tissue. There is some weight there, and it appears normal from a distance, but I don't actually feel anything discernable inside. He doesn't have any problems with ed beyond those that are normal for his age. Actually, we have a very active sex life. I asked him if he has noticed any changes in his testicles as far as loss of size and shape in recent years, but he doesn't examine and says he doesn't know, but hasn't noticed anything unusual.

I'm sure my observations and questions are insulting to his manhood even though I try to be as tactful as possible, but until I can get him to go to a doctor, does this testicle sound normal to anyone?