I only know that falling in love should be the happiest time of your life. You seemed so sad.

我只知道，恋爱应该是你生活中最快乐的时候。可是你似乎很伤心。

youdao

Be the one who can give a shoulder to her when she is sad, as girls are always emotional so make her laugh with your jokes sometimes and listen to her always.

做一个合格的倾听者：当她伤心时给她个肩膀依靠，女生永远容易受自己情绪影响，所以有时可以跟她说说笑话哄她开心，有应该可以耐心倾听。

youdao

One minute you might feel very sad, the next minute you may become frustrated with your fruitless efforts, time-wasting and seeing how everybody else seems to find life so easy.

这一刻你也许很难过，下一刻你也许会对你毫无结果的努力、白白浪费的时间和看到别人轻松的生活而倍感挫败。

youdao

One music expert said: "Your Cheatin' Heart" is so sad, it sounds like a judge sentencing somebody to a punishment worse than death itself."

VOA: special.2009.11.22

So, do your friends a favor and post a sad status update today.

FORBES: Do Our Happy Friends on Facebook Make Us Sad?

So this is a very sad time when a plant closes that's been the cornerstone of your community for, you know, most of the century.

NPR: U.S. Auto Industry Still Reeling