Ah, l'amore! While reading, we get to witness the sweet charms of young love as Hazel and Augustus flirt their way towards getting to know each other. Their attraction is undoubted, their compatibility uncanny, and by the end, we see that their love for each other is undeniable. But this isn't just a story about Hazel and Augustus—it's a story about everyone else in their lives, too. And there's a lot of love coming from all directions. If it weren't such a sad book, The Fault in Our Stars would be a pretty sickening love-fest.
Though Isaac thinks he has a handle on love at the beginning of the book, he discovers that promises are not what make up true love. Actions are.
Hazel and Augustus are never really in love—they're just feeling desperate and can both understand what the other is going through.