I think the song is about a guy who was being confessed to by his significant other, that she has fallen for his 'Friend', behind his back, due to his frequent absence in the relationship... and his friend being there to comfort her during his absence. Failing to tell him that she was not comfortable about his often absence, and that to her it seemed that she/their relationship is not important to him, and fast forward to the break up.
I think the song is about a guy who was being confessed to by his significant other, that she has fallen for his 'Friend', behind his back, due to his frequent absence in the relationship... and his friend being there to comfort her during his absence. Failing to tell him that she was not comfortable about his often absence, and that to her it seemed that she/their relationship is not important to him, and fast forward to the break up.