Separation anxiety

Remember how I said that Scruffy followed Shadow around like a puppy? Scruffy spent all of yesterday alone. He then spent the evening with me, because Shadow was in no shape to receive him. And while I don't know what he did in my absence, after Shadow and I came home he spent almost all of his time in his bookcase lair, until I foolishly made him aware of her presence in the apartment, in the bedroom area. Then he spent all of his energy doing two things:

1) trying to get to Shadow, and

2) trying to continue to avoid and hide from me.

Most of this consisted of sitting in front of the gate to the bedroom, sniffing at it, and occasionally trying to paw his way past it, but once Shadow had recovered enough that I turned off lights to try to get some sleep, Scruffy climbed up the pole to gain access to the bedroom, then quickly repeated this performance after I had chased him off and turned off the light again. Ultimately, I had to place one of the litter boxes in the kitchen and shut him in there for the night.

This leads me to wonder what he would do if she vanished for several days. If it weren't cruel to Shadow to send her off (does anyone know of a kitty sleep-away camp?) I'd experiment and find out, especially since I seem to recall reading that isolating a kitten from other cats can bring it to turn to people for interaction.

Though maybe that's a bit manipulative.