FO·MO
/ˈfōmō/
noun, informal
Fear Of Missing Out. Anxiety that an exciting or interesting event may currently be happening elsewhere, often aroused by posts seen on a social media website.

FE·LINE FO·MO
/ˈfēˌlīnˈfōmō/
noun, informal
Fear Of Missing Out as applied to cats. The anxiety that an exciting or interesting event may currently be happening elsewhere, often aroused by noises made by other cat(s) in the same space.

   
The older my cats get, the more they seem to care about what the other one is doing.

Jenny can be laying next to me purring away because she's getting petted... but then she'll hear Jake running around downstairs, worry that he's doing something super-fun that she's not a part of, then go ripping down the stairs to see what it is.

Jake likes to sit on my lap while I'm watching television. But the second Jenny goes running by to head out into the catio, he is all of a sudden paranoid that she's spotted something awesome out there, and is running after her to see what that might be.

My cats are in a perpetual state of FOMO.

Over each other, of course... not over me. They couldn't care less about what I'm doing.

Unless it's feeding them breakfast or dinner.