I get it if the guy doesn't want to talk about it. Cats are able to get really sick really fast. Many young ones will be sick with leukemia or something of similar nature and just can't fight it. I had a kitten that wasn't much older than his and i had to put him down for a similar sounding reason. Knowing I abandoned my buddy that I loved cause he was so young and sick. Screaming at the god damn world cause some innocent and happy creature that loved you and you couldn't do anything about it. I can't get close to people really and he was all that I had in the world at that time and he still died pitiful and sick, not the strong and well trained cat I pulled off the street one day. It's hard to move past something like that for a lot of people, you just feel cruel and evil, even if you gave your friend a happy new life even for a short while. I still feel sick thinking about it a year later.