down in the mouth 痛心（成语）
英文释义
(IDIOM) Sad; discouraged; lost in hopeless despair. (NOTE: sometimes hyphenated as "down-in-the-mouth").
例句
My son's favorite basketball team lost their championship game last night, so he has been feeling down in the mouth all day.
我儿子最爱的篮球队昨晚输掉了总决赛，他为此痛心了一整天。