I work in a rescue and you do get the heartbreaking cases where an entire family is huddled together sobbing as their beloved pet is put into a pen
there was one occasion when a rabbit we had rehomed had been bullying their bun despite a successful bond at the rescue and it got to the point where they needed to be separated, they brought the little guy back and as I took this little bunny out of the girls arms she just burst into tears
I felt sooo guilty. Once their rabbit had recovered a bit we bonded her with another bun and its true love and so another bun got a home, but the family still visit and send food and treats for the original little guy.
So it does happen that letting their animals go is beyond their control, but sadly from what I have seen most the time we get handed a carrier and then they ask for the carrier back
or look at you blankly when you ask them what the animal is called...
Personally I dont think I could do it, but if I knew that I could not provide what they needed and someone else could then I think I would make myself do it
sometimes letting the animal go is the only way to be kind