behavioral?

We adopted a 2 yr old male Russian Blue from a shelter about 6 months ago. He is extremely affectionate. I have a rescued female cat (5) that is also very affectionate. We have found the male has urinary crystals & is currently on medication and a special diet. He is spraying on the furniture, beds and carpet. The Vet says this is behavioral and has nothing to do with his urinary issues, but everything I have read say they can be related. He also is very jealous of the female. We had 2 other male cats, she was the alpha over all. The male wants to be the alpha. They refuse to get along, they hiss and fight at least once every couple of days. Since the male is ill, even if I wanted to give him up for adoption, I don't think anyone would take him. Any suggestions on how to get the two cats to get along? Do you think the spraying is behavioral?

The spraying is more likely to be behavioral than medical, particularly since this is the opinion of the vet who is managing his care.
   
You are not going to make two cats who don't want to get along to do so because you want them to, so frankly the best course of action is to nurse the male back to health and then re-home him.