updated 05/21/2012 AT 2:00 PM ET
•originally published 05/22/2012 AT 1:00 PM ET
Kelly Clarkson is known for empowering breakup songs like “Since U Been Gone,” but now that she’s happily in a relationship, the pop star is struggling to find her edge.
“It is killing me,” Clarkson told PEOPLE while doing press for ABC’s upcoming singing competition show Duets. “I’m trying to write a tough song and it is coming out like butterflies and rainbows.”
Clarkson, 30, says she has been dating Nashville-based talent manager Brandon Blackstock, 35, since late 2011.
“It is ruining my creativity,” she joked of the relationship that she publicly announced in early March. “I’m writing all this happy [stuff].”