She was with David Hodges from Evanesence but then he broke up with her and got engaged like a week later, thus inspiring Behind These Hazel Eyes & Never Again
Then she was with Graham Colton, this singer-songwriter dude. She broke up with him, thus inspiring Already Gone
Kelly is kind of selective with what information she shares and she's almost never in the tabloids.. she only gave this up because someone asked her directly in an interview if she was single. That's why you don't hear much about her previous relationships or anything. She keeps most of her personal life out of the public eye.