The Lover’s Dictionary by David Levithan. It pieces together a bittersweet love story through dictionary entries, each word having a significance in the relationship of our protagonists. It goes through a myriad of emotions one goes through a relationship - happy, sad, amused, irritated, brokenhearted, and hopeful.
An entry that summarized the book for me is:
Cue the imaginary interviewer:
Q: So when all is said and done, what have you learned here?
A: The key to a successful relationship isn’t just in words, it’s in the choice of punctuation. When you’re in love with someone, a well-placed question mark can be the difference between bliss and disaster, and a deeply respected period or a cleverly inserted ellipsis can prevent all kinds of exclamations.