You must let go of the idea that to be single is to be unhappy and unfulfilled.

你必须放弃单身就不快乐不满足的想法。

《柯林斯英汉双解大词典》

Tutu seemed to be unhappy.

图图看起来并不高兴。

youdao

You might be unhappy if you can't accept it.

如果你不能接受，你可能会不开心。

youdao

I thought I would be unhappy all day and things would not go well.

VOA: special.2009.05.03

Coz the comment that we get so often about this class ? is why would Harvard students possibly be unhappy?

因为我们得到的关于这门课的评价常常是,为什么哈佛的学生会不幸福？

哈佛公开课 - 幸福课课程节选

Would you be happy or would you be unhappy, to discover that you actually have been living ? a life on the experience machine?

你会开心还是不开心，如果你发现实际上,你一直都是在体验机器里生活？

耶鲁公开课 - 死亡课程节选

The bottom line, if you are looking for an excuse to be unhappy you will surely find it.

FORBES: Readers Say

They will be unhappy if they make more money than you do ( Social Forces, 2006).

FORBES: Careers And Marriage

And if they do have kids, they are more likely to be unhappy about it.

FORBES: Careers And Marriage