Resident Cat and N

LSS: I have had my cat Rorry since he was a simple cotton ball looking kitten. He is 3 now and has been solo dolo since. This said, the distribution system did it's thing and now I am a mother of two cats.

I am not sure of the new kitty's age, she seems older, but she is SO SWEET. Like this cat just wants love, let me bathe the dirt off her, trim her nails - an angel. I haven't had any contacts regarding owners and no chip was at the vet so needless to say she is staying. Rorry is not a fan and went from a happy go lucky cat to Oscar the Grouch very quickly. His demeanor changed so much that he even growls at me. I kept them separate but the hate for me hurts.

I grew up with dogs so I am not sure about timeline for this. The new kitty, Ushi, is very happy, but Rorry is being not himself.

Any advice would help as rehoming is not in the cards unless necessary.