I would say the ones being separated and going off feed are probably going off feed because there is a drastic change in their environment when they are placed in different containers. Balls will go off feed over just about anything. One of mine won't even consider eating if I've opened his bin at all the day before feeding day.

Snakes do not have the parts of the brain responsible for emotions like affection or sadness. They're not physically capable of experiencing those things.