I adopted two littermates, a boy and a girl a few months ago. They get along very well, but there is a problem: they cannot stand to be apart for even a few minutes. If I put one in the bedroom and shut the door, they will cry and scratch at the door and carpet until they are let out. My little boy is the worst; he will even start crying if his sister is just in the other room out of sight until she comes running or he finds her. This isn't usually a problem, but my boy likes to muscle in on his sister's food, so I'd like to start feeding them separately, but even food will not convince him to let his sister out of sight. I also need to get them fixed soon, and I'm worried about how stressed out he will be. Any suggestions on how to get them to start being more independent?
Separation anxiety aside, cats just don't like closed doors!
To deal with the feeding issue, perhaps you can arrange something where they are not really separated, but the female can protect her food a bit more easily. One option might be to find a cat-sized box, put it on its side, and place the female's food in it. Her body will block access to her food. Another technique I have used with success is to split the food up into three bowls, side-by-side or in a triangle. When the brother nudges the sister out of the way, she can easily move to another bowl. This tends to equalise the amount eaten by the two cats.
When you arrange with the vet to have them fixed, ask if they can be kept in one cage or in side-by-side cages until the operation. (After the operation they will be too drowsy to care.) Alternatively, you might arrange to have them operated on first thing in the morning. The vet can call you as soon as they are awake, and you can pick them up. That should minimise any separation anxiety.