Definition
To diminish someone's confidence or enthusiasm, typically by saying or doing something unexpected.
I was all set to tell him we were through, but he greeted me with a big bunch of flowers—it really took the wind out of my sails.
She was about to begin her presentation when a technical issue arose, which took the wind out of her sails.
I was very excited about the project, but when I found out the budget had been cut, it took the wind out of my sails.