Is this mean to the cat?

My girlfriend has a 6 yr. old cat. I have dated her for 2 years. Anyway I am severly allergic to her cat. I break out in hives and cant breathe. I take benadryl, makes me so tired. And I have taken chlortymaton (non drowsy form of benadryl) for the two years. It helps a little. But I can't take that for another ten years. Anyway we bought the cat a bunch of toys and goodies and put him in one room in the house, as opposed to having the entire house to himself like he used to. My question is, to see if this is mean to the cat. We still go in and pet him as much as possible especially my gf. He isn't acting out at all and the vet said that another cat may not be good, seeing how territorial cats are. Is it cruel to keep him in one room of the house, to help cut down on my allergies. I would never ask my gf to give up her cat. But I need to find a happy medium where he is happy and I'm not in hives and watery, red, itchy eyes. Let me know what you think. IThanks