It's Not the End of the World by Judy Blume

It's Not the End of the World was written by Judy Blume and was published in 1972.

Summary
Twelve year old Karen Newman has decided she'll never get married. Just look at her parents. All they do is fight. And now Karen's dad has moved out of the house and they're talking about divorce. But despite their fighting, Karen is sure they can work it out if they really try. Can Karen hold the family together-or is that really the best solution?"