Analysing my losses #2: What did I do wrong?

I've this friend of mine, which is only playing occasionally, but plays very strong. My overall stats against him are 2 wins, 5 losses.

Before this game I mostly forced tactical positions on him, which he handled rather well (like Kings-Gambits or the Schliemann). So this time I tried a more quiet Philidor, hoping to outplay him positionally.

I took this game very seriously and took plenty of time for almost all my moves. This is what happend:

So, I was outplayed and lost. But what exactly did I do wrong? It can't be just 25..Nd7.

The engine evaluation was almost always slightly better for white, during the game. But never much more than 0.5. It's also very tricky to learn from the engine, because it almost always gives like my line is -0.4 and the comp. line is -0.3 and this for a couple moves in a row, and it adds up. And this is pretty hard to grasp, I hope from the explanation of my thoughts you can help me out.

Thanks in advance for any feedback provided :)