"Moje žena nikdy není šťastná."

[AratAndrs1]

Why "My wife is never lucky" is incorrect?

[BoneheadBass]

Hmm. Since "lucky" appears to be a legitimate translation (see below), seems to me your answer should be accepted. Maybe it wasn't the anticipated translation, but it looks like it should be a valid one. You could report it, if you haven't already.

https://glosbe.com/cs/en/%C5%A1%C5%A5astn%C3%BD

[VladaFu]

You could use this as an adjective to describe someone or something. Štastná náhoda, Šťastný Jim, Šťastný Luke - lucky coincidence, Lucky Jim, Lucky Luke.

But it does not really work in "být šťastný", we say "mít štěstí" instead ("to have good luck").

[btopps]

I put "My wife is never not happy". How would you say that?

[Travis0]

That is the same as saying she is always happy. The Czech double negatives can be very confusing.

[artem10436]

Why "my wife is always unhappy" is incorrect?

[VladaFu]

Moje žena je vždy nešťastná. different sentence