Welcome Kauser,
It sounds like the environment or atmosphere in your home has changes drastically due to the sickness of your other Grey.
Your Greys were together, separating them is the first major change because they were "friends" and possibly mates?
He is the Male and the Protector of his Mate and is trying to let you know that he is not OK with this change in living arrangements.
To him, I would imagine this is an act of aggression on your part and the chasing him around the room with fabric just put the icing on the Cake.
I would give him his space for now and once the Female has overcome this disease, you will be able to place them back together.
Once the reuniting takes place, I would think He would start lowering his aggression and protection mode regarding the welfare of his mate.