rain on someone's parade
US /reɪn ɑn ˈsʌm.wʌnz pəˈreɪd/
UK /reɪn ɑn ˈsʌm.wʌnz pəˈreɪd/

1.
水を差す, 邪魔をする
to spoil someone's pleasure or plans
:
•
I don't want to rain on your parade, but I think you should reconsider your decision.
水を差すつもりはないけど、決断を再考すべきだと思うよ。
•
He always manages to rain on someone's parade with his negative comments.
彼はいつも否定的なコメントで人の気分を台無しにする。