Why did he resign

https://www.chess.com/live#g=18757226285

Idk why he resigned

I defended with the Scandinavian Defense.

He took the pawn i took the pawn with queen.

Then he blundered his queen and i took his queen with my bishop.

Not sure, but you played a good game.

btw, here are a few "chess opening principles" I mentioned in the annotations:

https://www.chess.com/blog/KeSetoKaiba/opening-principles-again