What is the background of this male kitty? It sounds like he is very unsure of other cats. He is attacking ALL of your 3 cats? You said that he is very loving toward you. He may very well be afraid of your cats. I agree that some cats would be better as only cats. This could possibly be one but I would still try the seperation. He may need a little longer to adjust. After all, He has 2 young females to contend with How are your other 3 kitties reacting to him?