Textbook deus ex machina ending.
An inane, contrived story. The illustrations are kind of cute, kind of smudgy. It was written in 1940 and it's pretty dated.
A little girl lives with her parents and a cat in an apartment in New York. The father says it's a "one-cat apartment." And then the cat has three kittens, and the little girl falls in love with one of the kittens, but doesn't tell anyone because she doesn't want to play favorites, and really she wants to keep them all. Two people come by and each of them adopts a kitten, luckily not the one the girl has fallen in love with. Of course. Because that would just be sad. The parents decide that the girl would like to play with the kitten more than the adult cat, so they plan to get rid of the adult cat. But the little girl realizes that the cat is going to go to her aunt's house, where nobody really wants her, and she feels sad and worries about the cat and what's going to happen to her. She declares that she wants to keep the cat and give away the kitten. Then they suddenly decide to move to a larger apartment. The end.
Their excuse is that the little girl is growing out of her small bed and will need a larger one which won't fit in the apartment, but that seems like something you should think about before having a child in a small apartment. Seriously. It's just dumb.