Based on this.
Blaine sat on his bed, fingering the fabric of the red gown in his lap. “I can’t believe I’m graduating.” He said, laughing a little.
"What, did you think you were gonna fail?" Kurt asked jokingly from Blaine closet where he was currently going through Blaine’s clothes for no apparent reason.
"No." Blaine said thoughtfully, "I knew I’d never fail. It’s just…it feels like it’s been so long."