take the wind out of somebody's sails
take the wind out of (one's) sails
1. To diminish someone's enthusiasm, excitement, or positive outlook (about something). She thought she'd won $1 million, but when I told her the letter was a scam, it really took the wind out of her sails. It took the wind out of his sails to learn that nearly half of his Christmas bonus would go to taxes.
2. To deprive someone of an advantage; to make a situation unfavorable or detrimental for someone. The crowd's deafening applause for the home team took the wind out of their opponents' sails. Learning that the boss was letting Jenny give a proposal for the project as well really took the wind out of my sails.