"When you were mine", by Prince.

Verse (repeat the following):
|> G --------------------
|> D --------------------
|> A ---------------2----
|> E -2----2---2---------
      When you were mine
|> 
|> G ------------------------------
|> D ------------------------------
|> A -0---0---2-----4---2----------
|> E ------------------------2-----
      You were kinda my best friend