I thought you'd go
But you were with me all along
Macklemore thought his addiction to codeine had gone after he had been clean for 3 years, but it was with him the entire time, and he realizes that after he relapsed.
Another interpretation could be that Macklemore thought he was alone in fighting his addiction, but his family and friends (such as Ryan Lewis) were always there for him
To help improve the meaning of these lyrics, visit "Starting Over" by Macklemore and Ryan Lewis (Ft. Ben Bridwell of Band of Horses & Macklemore) Lyrics and leave a comment on the lyrics box