Yes, not all cats get along. My RB Peeka hated Pidge, hated her! She attacked her every chance she got, stalked her, waited for her to come out of the litter box, etc. Pidge spent a lot of time under my bed until Peeka finally let up but still, every once in a while, she'd strike. Cats are individuals just as people are. Not all people get along so why should we think that all cats will? And what is a cat therapist anyhow?