Lauren Oliver said this quote

Things weren’t always as good as they are now. In school we learned that in the old days, the dark days, people didn’t realize how deadly a disease love was.For a long time they even viewed it as a good thing, something to be celebrated and pursued. Of course that’s one of the reasons it’s so dangerous: It affects your mind so that you cannot think clearly, or make rational decisions about your own well-being. (That’s symptom number twelve, listed in the amor deliria nervosa section of the twelfth edition of The Safety, Health, and Happiness Handbook, or The Book of Shhh, as we call it.) Instead people back then named other diseases—stress, heart disease, anxiety, depression, hypertension, insomnia, bipolar disorder—never realizing that these were, in fact, only symptoms that in the majority of cases could be traced back to the effects of amor deliria nervosa.