I’d tell you I love you but then I’d have to kill you by Ally Carter

“Plot. A young spy, Cammie Morgan, falls in love with a boy, Josh, but cannot reveal the truth about herself to him. This caused misunderstandings later on and they broke up in tears. In the end, Josh finds out about her being a spy, and all wrongs in the past had been corrected, and hope came back to Cammie.”

Paperback