Middlegame issues part 3

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maremar3

According to the engine, I missed an opportunity here. In this position, I played a6 to remove the bishop that was pinning my knight. However, the analysis preferred e4 instead. I don't quite understand why I should play e4, as it seems to allow Ne5.

Now, I feel compelled to capture the knight, either with my own knight or my bishop, but I’m struggling to see what I truly missed by choosing a6 over e4.

What can I learn from this position?