Please Help. Song heard @ Forever 21. "he was my sweetheart..(?)"

Hi. I heard a song at Forever 21 a few days ago. The singer was female, it sounded a bit techno pop-ish (similar to Metric), it was upbeat, and the lyrics were...

"He was my sweetheart. Now he's gone and I'm better off without him"

but I could be remembering the lines wrong. maybe it was....

"You were my sweety. Now you're gone and I'm happier without you"

or any variation of that. . The girl had a 'sweety' or 'sweetheart', he left/ is gone, but she's better off/ happier. Sorry I can't remember the exact chorus words. I've searched for the lyrics everywhere, but can't find it. Please help! It's NOT Avril Lavigne or Ashlee Simpson. I know that much for sure.

Also, the Forever 21 store was in the San Francisco bay area... at either the Tanforan mall or Serramonte (just in case shop location helps).


Any help would be most appreciated!