My housemate's little black puppy died one evening when I was responsible for him.
I didn't realize the window was open. He galloped across the room, jumped right out, ran across the yard into the street where he was hit immediately by the first car that passed. It all took about as long as it took you to read this paragraph.
He was alive when I reached him. I don't think he was in much pain. He wasn't crying. He licked my hand, and he died.
The lesson I learned was that I wasn't responsible enough to be in charge of another life. I asked my mother to adopt my cat, who gained about ten pounds now that she was fed regularly. The cat, not my mother. Forever after I've lived without animals.
It leaves you more free, I guess. You can pack up and go anywhere you like, anytime you like. You're tied to nothing but your rent payments.
But it's a loss. As though your life were flattened by the removal of an important dimension.
Time to go play with Maggie, my neighbor's old black Lab.