Every once in a while, a cheesy romance novel (or series) becomes popular. This time it's Colleen Hoover. In the past, it was the 50 shades of Grey, Twilight series, etc.

Not every book is a masterpiece, but it's still popular because it hits the right spot for the people who like reading these books. Not everyone wants to read classics or deep narratives. I'd say that the main reason why people like this book is because it's a form of escapism from their mundane life. There's something appealing in witnessing a fantasy relationship that is either personally satisfying or deals with other people's problems. It's like watching a soap opera. The dialogue is terrible, but you really want to know what happens next because you're emotionally invested in the characters.

It's like any other movie that makes a lot of money but gets a low score from the critics.