He was in love with this woman who took the relationship they had like a game. She was using him for sex and after each time, she'd say goodbye like it was nothing till she needed more from him. Eventually, he got sick of it and she knew it and didn't want him to say goodbye. As the song says, he wont say goodbye anymore, which means he is done playing the game with her. At the end of the song, he gives her everything she wants, and he is the one who ends it for good, never saying goodbye to her. This loops back to the beginning of the song where he whispers it to himself.