Where you Belong by NaomiRaven
Kurt receives flowers and a note asking him to Dalton's prom. The name signed on the note is Blaine. Blaine, however knows nothing about the flowers or the note and thinks Kurt already has a date to the prom. On the night of the prom Kurt thinks Blaine stood him up until he finds out that Blaine wasn't the one to send the flowers. Kurt is then upset and thinks that someone did this as a prank.
It was actually Jeff and Nick that sent the flowers, but they did it to get Kurt and Blaine together.