I am looking for a specific story. Klaine was married and Kurt was a fashion designer while Blaine was a teacher. Both thought the other has easier job and one day they woke up in the other body. They tried to live the other life, and realized they were wrong.
I remember Kurt didn't knew that Blaine had problems with his class, and Kurt only realized when one of Blaine colleague speak with "Blaine". Kurt did a as Blaine a teacher-parent conference thing too.