"It Ends with Us" follows the story of Lily, a determined woman who builds a successful life in Boston. She meets Ryle Kincaid, a charming neurosurgeon, and believes he is her perfect match. However, as their relationship deepens, troubling signs in Ryle's behavior emerge, forcing Lily to confront difficult truths about love and loyalty. The reappearance of her first love, Atlas Corrigan, further complicates her emotions and decisions.

The key themes in "It Ends with Us" include domestic abuse and toxic relationships, forgiveness and second chances, and personal growth and empowerment. The novel sheds light on the complexities of abusive relationships, the importance of forgiveness, and the journey of self-empowerment.

"It Ends with Us" addresses domestic abuse through Lily's experiences, highlighting the emotional turmoil victims face and the strength required to break free from such cycles. The novel emphasizes the importance of recognizing and addressing toxic behavior and the courage it takes to leave an abusive relationship.