Playing well results in more wins.
A loss doesn't mean you deserved to lose. Because variance exists, and there are elements of the game are out of your control, you can't rely on the outcome OF ONE GAME to tell you anything.
Variance is eliminated through volume of games. Playing a high enough number of games, while playing better than your opponents, will cause you to rank up. Does the outcome (win/loss) of one game mean anything? No. Does the outcome of 100 games mean something? Yes, absolutely.
So when analyzing the one game, the only question you can ask yourself is, "did I play well?". And if the answer to that is yes, then don't allow the outcome to mean anything, whether it is a win or a loss.