So Long and Thanks for All the Fish (1984) was the fourth book in the Hitchhiker's Guide to the Galaxy series by Douglas Adams. In this book, Arthur returns to the earth to find it mysteriously reappeared, only to meet the an enchanting girl over and over again through improbable circumstances.
If you've been reading this series, you will discover that this is the best written manuscript to date. This tale is more of a romantic comedy than a space adventure, where a little human happiness and love are the central part of our story. Also, there's the mystery of why the Earth shows up again, but once the romantic comedy starts, you don't care. You just accept that the Earth is back and Arthur gets to see the world in it's inexplicable ordinariness.
Here is the book where Douglas Adams' genius really takes off and stays up.
The girl in question is mentioned in the Hitchhiker's Guide to the Galaxy as that girl that finally figured out what was wrong and how to solve everything. This isn't a spoiler as you learn that much in the first three pages.
On the whole, the pacing is relaxed but not slothy, exciting without anxiety, humorous as real life, and as lively as humor. I think it's as solid a ramble as you're ever likely to find. The main difference between this book and a real romantic comedy is that this book is far more believable.