A sad move, but the d6-pawn requires protection.
1. d2d4  1... g8f6  2. c2c4  2... g7g6  3. b1c3  3... f8g7  4. e2e4  4... e8g8  5. f1e2  5... c7c5  6. d4d5  6... d7d6  7. h2h3  7... e7e6  8. g1f3  8... b8a6 [%c_effect a6;square;a6;type;Inaccuracy;persistent;true] This is too slow, and White gets a comfortable advantage. 9. e1g1  9... a6c7  10. a2a4 A good move, avoiding any chance of b7-b5. The alternatives also lead to an advantage. 10... c7a6 The knight returns in order to go to b4. 11. d5e6 [%c_effect e6;square;e6;type;GreatFind;persistent;true] An excellent moment to change the pawn structure. 11... c8e6  12. c1f4 