When things get hot and heavy between Will and Lake they call out a point of retreat. Is it effective? Yes. Even though they both promised Lake's mom before she died of cancer not to have sex for a year (a long, whole year), I believe, were she still alive, she'd be as surprised as me that they followed through.
The truth is true love reigns between Will and Lake. They are open with each other, sharing their ups and downs everyday. But when Will's ex-girlfriend makes a reappearance to claim him back, things between them start to go sour.
Having Will narrate the book is a lovely surprise. His voice is more mature than Lake's. Not to mention more romantic. It was important to be in his head to see how his ex girlfriend's presence affects him. Colleen Hoover might not have included as much poetry as she did in Slammed, but it's filled with enough tears and romance to make any reader hug whoever is nearby. Just make sure to call out a point of retreat if things get too hot.