I've had so many conversations about 'It Ends with Us' with friends and fellow readers, and the age appropriateness question always comes up. Colleen Hoover's novel deals with really heavy themes—domestic abuse, toxic relationships, and emotional trauma—but it's written in a way that feels accessible, almost deceptively easy to read. That's what makes it tricky. I'd say it's best suited for older teens (17+) and adults because younger readers might not have the emotional tools to process the intensity of the subject matter. The way Hoover handles Lily's journey is raw and honest, but it doesn't glamorize the pain; it just lays it bare.
That said, I wouldn't gatekeep it from a mature 16-year-old who's already engaging with serious topics in other books or media. It's more about the individual's readiness than a hard age cutoff. I first read it at 22, and even then, some scenes left me emotionally drained in a way that made me grateful I’d waited until I had more life experience. For younger readers, it might be worth pairing it with discussions—whether in a classroom, book club, or with a trusted adult—to unpack the heavier moments. Honestly, it’s one of those books that lingers, and not everyone’s prepared for that at the same age.