I am not sure it is only passion about a particular composition. It could be a composer's style, a particular genre or category, or simply a passion for music, defining and performing your personal interpretation and sharing your interpretation with others. I guess I am saying there are many reasons why we may reveal passion when we play the piano. In that way we are all distinctly individual, unless of course we merely play notes and concern ourselves with accuracy only.
A teacher of mine said "Learn to sacrifice your babies." That shocked me because it sounded so violent! But what she meant was, in music do not treat how you play a piece as a precious baby, it will change, you will have to let it go as it evolves. We can get depressed if we find the "new way" is much more superior to what we where doing before but to do it we are faced with another hill to climb.
Don't feel too bad about people pointing out what they think is not completely correct in your playing. They are relating you to a perfect model and no one can play at that level. I can even critique the best pianists in the world but it doesn't really matter because what they play is very entertaining and enjoyable to listen to!
To improve however is a tough road, and people get depressed, demotivated. This is what separates the mediocre from the outstanding. The outstanding practices even though they are beaten down, the mediocre give up and throw it away when things get heated. Sometimes a teacher is nice not so much for direction and guidance, but to have a buddy to share music with and bounce ideas with. Someone who is interested in your personal journey through music. Sometimes when you are by yourself, you can feel so alone and flounder.