Trapping your own Queen

In this position, black had intentions of playing Bh3 before my knight got to e4 from c3. Even without the knight on e4, Bh3 would fail to win the rook on f1 because of white's response Nh4. Black would then play his queen to f6, attacking the knight on h4 and avoid losing a piece.

Back to the position on the right, I played 8. Ne4 with the intention of capturing the bishop on d6, ending up with the bishop pair. The knight on e4 also takes away the f6 square from the black queen. Black moved 8... Nf6? With the knight on f6, the black queen is boxed in on the kingside. Black needed to keep the f6 and e6 squares available for the queen. I went after the coralled queen with 9. Nh4 and the black queen has no place to hide. White's bishop pair, the two knights and kingside pawns work together to cover all the squares in the kingside. Black had effectively trapped his own queen by 8... Nf6.