Cats don't like change so I'd say that this is most likely the cause. Even though my RB Starr and my Pearl weren't really buddies, ever since Starr's been gone Pearl has been extra clingy and needy towards me and it's been a little over 6 months now. She's always been very vocal so this sure hasn't changed. As my Storm has gotten older he's found his voice and he's also much more vocal especially about feeding time.