"You can't out-think bad luck."
Often, inexperienced players will lose because they're oblivious to everything you did during a game to maximise your chances of success, and will simply say that you were lucky at the end of it. This is mildly infuriating, but it's also something I want to be clear that I'm NOT saying here!
In Carcassonne, you have to plan to benefit from the most likely outcomes. There can be a lot of maths, strategy and tile-counting behind this, but even at a very basic level you wouldn't plan to take control of a city via a cccc tile if you can see that the only cccc tile has already been placed elsewhere since the chances of this succeeding would be 0%! So you try to give yourself the best possible chance based on what knowledge and information is available to you, as what's probable is by definition likely... but not guaranteed!
Consider the situation where you have a nice city waiting to be closed. It needs a ccfx tile to complete and your opponent has created an opportunity to kill it by potentially pointing a road into the gap unless you defend it on this turn. Thankfully your tile is a cfff which is ideal, but how best to rotate it? Looking around you can see that three of the four cccf tiles have already been placed giving you a 50% chance of finishing the city if you point the city cap into the gap. Alternatively, just two of the ccff and one of the ccff splitter tiles are out meaning there are four tiles that would fit if you use the tile to create a ccff gap which you'd have a 15 in 16 (93.8%) chance of filling. So which do you choose; the 50% win or the 93.8% win? That's not even a question as we all know what the right thing to do is in this situation and a lot of Carcassonne is about understanding this and making decisions which give you the best possible chance of success.
But like I say, nothing is guaranteed, and in the example above, having created the ccff gap, I wouldn't be at all surprised if my next tile was the final cccf and then my opponent laughs smugly and berates me for making a "bad move" to unsettle me. Next goes the other splitter (to my opponent), swiftly followed by all three of the remaining ccff tiles which seals the fate of my newly-ruined city. If I'd just rotated the tile the other way I could have have completed the city and won the game! But why would I have done based on what I knew at the time? It remains the correct thing to have done even though it didn't work out on this occasion, which can make situations such as these especially difficult to learn from. If you want to take away something positive from it then maybe focus on what else you might have done to have hindered your opponent or generated points for yourself elsewhere in the game. Could you have won despite the city being incomplete?
Ultimately though, never beat yourself up for doing the right thing. Sometimes the tiles are just against you (and sometimes they're not!)
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