Natural, or Lazy?

MY round five game at Jersey was heading for a draw until I played a "natural" move in the following position. Can you work out what it was, and why it lost material?

Black has just played 31...Ba6-c8 in Spanton (1851) - Richard Bryant (1932)

I lazily played 32.Ke2? (32.Kd3? is just as bad), losing a pawn, and eventually the game, after 32...Bf4.
Correct was 32.g3, after which neither player can realistically make progress.