I used to be able to read just about any chick flick or romance novel in a couple of days and find it enjoyable, but with time I sensed myself getting more and more picky. Whether it was the fruit of maturity, or just because I have less time to read for leisure, it has become increasingly difficult to find books that grip my attention to their last page. On the other hand, although I enjoy reading more sophisticated literature once in a while, I miss reading to give myself a break, the sort of book I can get lost in with little concentration required, appropriate for reading in public transportation or before bed when you are too sleepy to think properly.
These book recommendations are sincere, from someone who grew up reading Jacqueline Wilson, went through a Twilight phase, read all trashy chick-flicks that enjoyed 10 seconds of fame when they first came out, and has emerged alive and with a better (or more age appropriate and socially acceptable) taste.
For fans of John Green, or generally for anyone looking for a light read, chick-flick in which all characters have deeply developed personalities. Focus is more on relationships (both platonic and romantic) rather than on an exciting plot:
The Beginning of Everything by Robyn Schneider
Fangirl by Rainbow Rowell
Chick flicks that discuss psychological phenomena (both traumas and psychological disorders). Not so much of a light read, but definitely have the chick-flick feel to them and don't require a lot of concentration:
The Perks of Being a Wallflower by Stephen Chbosky
Hopeless by Colleen Hoover
More on the fantasy side, but these definitely include a lot of romance and interesting platonic relationships. Both are relatively long book series, but every single volume is a page-turner:
The Mortal Instruments by Cassandra Clare
Throne of Glass series by Sarah J. Maas
If you are a fan of historical fiction, or even if you aren't:
I decided to include Phillippa Gregory in this list as her books read like chick-flicks in the sense that they focus on human relationships and are easy to read page-turners. Although some historians have debated the historical accuracy of her books, I find that they do help you get a general understanding of events during the period in which they were written, or at least they make a history class much more entertaining, as I definitely feel like I know some of these historical personas personally. I would especially recommend her books for fans of television shows such as Reign and The Tudors.
Gregory has written various books on English history, and I would especially recommend The Other Boleyn Girl, The Virgin's Lover and Three Sisters, Three Queens.
If you want to read about adults (as opposed to high school or college students) in the real, modern world: