AUGH! I can't wait to wade through all the responses above me, so let me just say: if your husband is concerned about the cat's happiness and well-being, ask him to try to imagine this...
Your husband grows up a perfectly normal, happy little boy, living in his happy little household, until one day the testosterone kicks in, and he starts having... d e s i r e s.
upon those d e s i r e s,
he needs to leave the house and find himself a girl. He wants this very badly. And as he grows older, he wants it more, and more, and more. By the age of 18, he's flinging himself bodily against the walls
to try to get outside and find a girl.
But he's not allowed
Because it's irresponsible, and there are too many diseases and too many dangers and far, far too many kittens born into this cruel world.
So all his life,
he will have to live with these unfulfilled d e s i r e s.
And as any red-blooded man will tell you, that's nothing less than torture.
And that's a pretty good analogy to how it is for an unneutered male or unspayed female cat. Their "d e s i r e s
" are perhaps even more desperate than ours, because theirs are purely
instinctual -- cats are not able to reason or rationalize or take up chess instead.
Y'know, breeders have to keep intact kitties, of course, and they have to keep them apart except for selected mates at selected times. Maybe it would be helpful to your husband if someone in the Breeder's Corner forum would talk about what that's like...